Julia Fox, Diamond in the Rough of ‘Uncut Gems’

“It was fantasy role play. I’d have one minute before a session. They’d give you a piece of paper with the guy’s info. ‘O.K., he wants me to be like his angry mother. Got it. Boom.’ And, you’ve got two seconds to get in that mind-set.”

Ms. Fox added: “I went in there insecure and with low self-worth. I didn’t understand my value. I left with too much self-esteem. Nobody was going to ever cross me again.”

Sometimes a listener might wonder is Ms. Fox is exaggerating, especially when she is offering her story in quick summary, as she did earlier that day at Lucien, a bistro and longtime haunt of hers. Before she could take off her fur-lined leather coat, she was greeted by two of the three diners sitting inside the virtually empty restaurant.

“I’m not going to lie, I woke up at noon, and I was like, ‘I’m going to have to shower and plan an outfit.’ So, this is what you guys got,” Ms. Fox said, glancing down at her sheer silver top. She ordered cauliflower soup and, festively, oysters, It was her one-year anniversary of marriage to Peter Artemiev, who works in private aviation in Brighton Beach, and whom she met through Lucien’s proprietor, Zac Bahaj. “We actually both forgot because I got one of those alerts on my phone.” She said she manifested him, too. (“Like ticking off boxes on a checklist, he was everything I said I wanted.”) Two months later, they were married.

Ms. Fox wasn’t a lock for the role she had shaped. The addition of Mr. Sandler and the powerful producer Scott Rudin to the project meant that beyond manifesting her acting career, she’d also had to earn it with a screen test.

“Pretty much every single girl in New York auditioned for the role of Julia,” Ms. Fox said — around 200 by the Safdies’ count, and some very well-known. “And they all knew that it was my role. It was so awkward to run into these girls: ‘Hey, I think I just auditioned for this movie that’s based on you.’ They thought it was a movie about my life.”