It’s been almost three years since, on Jan. 6, 2021, Ivanka Trump, swaddled in a black coat, stood beside her father inside a tent on the Ellipse in Washington, D.C. Until her walk up the steps of the New York State Supreme Courthouse on Wednesday, that was one of her last public family appearances in an official capacity.

In a hand-held video from 2021, she and Donald Trump are glued to TV coverage of the crowd, still figures in a fishbowl of pre-riot excitement: Kimberly Guilfoyle swaying to Laura Branigan’s “Gloria” and Mark Meadows bustling into the frame, and someone, barely able to contain their excitement, shouting “We have to have snacks!”

Then images of a noose in front of the Capitol were broadcast, “patriots” bashed and bear-sprayed cops, and Ms. Trump reportedly begged her father to ask them to go home.

Ms. Trump, a former senior adviser to the president, the female face of the Trump Organization, then stepped off the public stage. She’s been living in Florida with her husband and kids and, with the exception of a few family gatherings, hasn’t appeared in photographs with her father since. This week she faced a choice: stand by her father again or show herself an independent person with a head for business and a sense of civic duty and moral responsibility. Could she separate herself from the House of Trump?

The woman Republicans once talked of as a candidate for president — after her dad’s eight years, of course — is both known and a cipher. “I would sit next to her every once in a while at a dinner,” Barry Diller said to Maureen Dowd in 2018, just over a year into the Trump administration. “And I, as everyone did, was like, Oh my God, how could this evil character have spawned such a polite, gracious person? I don’t think we feel that way now.”

Alexandra Wrage, the founder and president of the international business corruption watchdog Trace, told me, “I don’t think there is any way Ivanka could have operated in these circles for as long as she has, in the shadow of her father, with these thuggish characters, and not have had questions about the qualities of her business partners.”

When the New York attorney general, Letitia James, charged members of the Trump family with inflating the value of key assets in order to secure more favorable financing, Ms. Trump got her own lawyer to represent her interests apart from those of her family. An appeals court later removed her as a defendant because of New York State’s statute of limitations.

Prosecutors subpoenaed her as a witness. They seemed to have in their possession way too many Trump Organization documents with her arabesque signature and too many of her emails in which nine-figure loans were being discussed. For years she had served as, at the very least, an elegant executive assistant opening the door between money and her dad.

Before her stint in Washington with her father, Ms. Trump was pals with the children of the American aristocracy — even if their parents scorned him as a parvenu and a golf cheat. A granddaughter of a woman who worked as a maid in the Carnegie mansion and a great-granddaughter of the widowed German immigrant who gave the Trump Organization its start, Ms. Trump was the first Trump woman to the manner born. For that, even more than the beauty her father frequently and creepily extolled, she played a special role in the Trump Organization.

She was in awe of her father in return. Aware of her father’s expectations about women within camera frame of him, she styled herself to doll-like perfection. In her book “The Trump Card: Playing to Win in Work and Life,” Ms. Trump used the word “brand” dozens of times. She lauded one of the secrets of her father’s special genius: optics. “Perception is more important than reality. If someone perceives something to be true, it is more important than if it is in fact true.”

That sleight of hand, which could be the family’s unofficial motto, is the heart of the case against the Trump Organization. While the country continues to debate the reality-show businessman’s real net worth, should we also be asking if his daughter was anything more than window dressing for her father?

For five hours, she answered questions in the rounded vowels of the American patrician, unfailingly polite, from the same witness box where her father and two brothers already testified. The only time she seemed slightly unnerved about the prosecutors’ line of questioning was when she was asked to talk about Trump Organization business emails she had forwarded to her husband, Jared Kushner, then the owner of The New York Observer. Around 2011 he introduced the Trump family to Rosemary Vrablic, who was with Deutsche Bank and later wrote many of the Trump loans discussed in the testimony.

Mr. Kushner is neither a defendant nor a witness in the case, but it seems he was a kind of consigliere. To one of the emails Ms. Trump forwarded to him about the Trump International Hotel in Washington, he replied, “You can get better pricing for such low L.T.V.,” or loan to value. “Natixis will give you 140 million at that rate, most likely. Should I show it to them?”

Asked on the stand about forwarding Trump Organization emails about a “potential transaction” to Mr. Kushner, she implied that it was a routine conversation between husband and wife: “My husband also was in real estate and would have perspective for me,” she said. “I recall telling him. I don’t remember the exact exchange, but it was not uncommon that I would ask my husband’s perspective on something that I was working on.”

It was a virtuoso performance on an ignominious stage. Ms. James, whom Mr. Trump has nicknamed “Peekaboo” — which some have criticized as a racist dog whistle — and who has been called “just not that bright” by one of his lawyers, sat in the front row, about 20 feet away.

“At the end of the day, this case is about fraudulent statements of financial condition that she benefited from, she was enriched,” Ms. James said outside the courtroom. “And clearly you cannot distance yourself from that fact.”

On cross-examination, Mr. Trump’s lawyers asked Ms. Trump about her role at the Trump Organization. “I feel incredibly proud of the work I did,” she said, mentioning the Trump International Hotel and the Trump National Doral Miami. “As I testified earlier, they were complicated projects. And I believe that we overdelivered on every metric in bringing them to fruition, as evidenced by the fact that they are both flourishing to this day.”

With that, she was dismissed, the last of 25 witnesses the attorney general’s office will call.

“The daughter will take down the father,” Steve Bannon once reportedly predicted, after Ms. Trump and Mr. Kushner helped persuade Mr. Trump to sack his F.B.I. director James Comey. If she was ever going to bring him down, it was this week. She didn’t.

She wouldn’t. She was the female future of the Trump brand, raised in the gilded tower Dad built, with a taste for power and power chairs, and he gave her that, the West Wing office and the woman stuff as her charge. She offered him elegance and old money diction and bulletproof resistance to humiliation. And for cognitive dissonance, no one better: She tweeted support for Time’s Up when the time came. Sometimes he even listened to her. She — or her tears anyway — may very well have helped extract the public apology for the “Access Hollywood” tape.

But a lot has happened since that afternoon in the tent on the Ellipse. She’s lost her mother, her husband had a second surgery for cancer, and his signature achievement, the Abraham Accords, is burnt paper in the Gaza-Israel war. And her father, the role model trickster and brander, faces 91 criminal charges in three states and the District of Columbia.

A broken doll, maybe, impeccably repaired, she didn’t flinch passing the small crowd of New Yorkers chanting, “Fraud family!” Her dad and her brothers and the New York attorney general appear to have finished off or, at the very least, vastly diminished the business that her great-grandmother started but for which she got no credit — credit that could have made for such great optics, if only her dad had been willing to give a woman credit and to celebrate that he was a son and grandson of immigrants.

Maybe power tastes like ashes now.