Sarah Paulson is arriving at the Toronto International Film Festival with a film role she says she did not know would ever come her way.

The actor stars in “Closing Night,” the filmmaking debut of Cody Fern, her “American Horror Story: Apocalypse” castmate. Fern wrote the part specifically for Paulson after working with her on the Ryan Murphy series, where, according to the source material, he was struck by her work embodying three distinct characters.

In the film, Paulson plays Sandra Vale, a glamorous movie star who gathers her estranged sister, played by Naomi Watts, her nephew, played by Toby Wallace, and his girlfriend, played by Odessa A’zion, for the opening night of her Broadway play. Sandra collapses onstage, and the incident, along with a diagnosis that Paulson said will not yet be revealed, sends the family into a reckoning. Dianne Wiest appears as the family matriarch.

For Paulson, the movie is not just another prestige drama. It represents the kind of substantial film showcase she says has been elusive, even after one of the most decorated performances of her career.

“If my work in this movie is any good, I just hope it leads to more opportunities for good parts, and I don’t care where they are. That’s the truth,” Paulson told Variety. “My hopes and dreams and fantasies have already come true in ways I could have never imagined.”

A role written for Paulson

Paulson and Fern’s creative connection traces back to “American Horror Story: Apocalypse,” where he played the Antichrist and she appeared, as she clarified, first as Venable, the ruler of an underground bunker, and also as a witch. Paulson said their friendship and mutual respect began there, though she did not know Fern had another major skill set until he sent her the script for “Closing Night.”

Her first reaction was disbelief.

“I thought he must have sent it to Cate Blanchett or Kate Winslet,” Paulson said. “It’s a part in the film space that I haven’t had the opportunity to embody.”

She said she has had “spectacularly rich and deep, complicated roles” on television and stage, but not a film opportunity of this scale “in a good while.” Knowing Fern had written Sandra for her added pressure. On the first day of shooting, Paulson said she worried, “What if I’m nothing like he expected or hoped or dreamt I would be?”

Paulson said part of the draw was the chance to play a woman confronting a health crisis and the psychological impact of her body changing. She also connected to Sandra as someone whose sense of purpose is tied to work, and who must confront what remains if that work is taken away.

The prospect of acting opposite Wiest also mattered deeply to her. Paulson called Wiest one of those performers “where those who know know there is no one better than she,” and said the chance to work with her was difficult to process emotionally.

Paulson also said she wanted to support Fern as he stepped into filmmaking for the first time. “I was moved by his bravery,” she said, adding that she believes he might have had more money or distribution if he had chosen “a bigger actress,” but that he wanted her.

The film offers that did not follow “O.J.”

Paulson’s comments about “Closing Night” come against the backdrop of her experience after “The People v. O.J. Simpson: American Crime Story,” in which she played Marcia Clark. The source material states that Paulson won every major award for that performance, becoming the first actor in history to do so.

But Paulson said the expected wave of film offers never arrived.

The first person to approach her afterward, she said, was M. Night Shyamalan for “Glass,” which she described as a sequel to “Split,” and that came “nine to ten months” after the show. “Ocean’s 8” followed, but Paulson said that opportunity came only after another actress passed on the role.

By contrast, she said her “O.J.” scene partners Courtney B. Vance and Sterling K. Brown moved into major film work. Paulson noted that Vance did “The Mummy” and that Brown did two movies between the show’s release and the Emmy Awards.

Paulson said she could only attribute the difference to being a woman and to her age at the time. She was 41, and she had played a character who was not hyper-sexualized and who, depending on the viewer, could be seen as unlikable.

“I found Marcia Clark to be very beautiful, but that is not the thing that she led with,” Paulson said. “She led with her brain and her fiery personality and her ability to hang with the boys.”

Speaking more bluntly about the lack of comparable film momentum, she added that she was “middle age and not playing a glamorous lady” and “wasn’t this hot, young nubile thing.”

A decade between major film showcases

Paulson said she is now 51 and that “Closing Night” was made in January. At the time of the conversation, she said it had been six months since the movie was finished.

The last time she felt she had something “really special” to do in film, she said, was “Blue Jay” with Mark Duplass, a small movie she said was shot in nine or ten days with a lot of improvisation. She described that experience as rich and special, but said it was 10 years ago.

“This is the first time I’ve had something in the film space that has felt this robust,” Paulson said.

She also credited Ryan Murphy with repeatedly giving her complex opportunities on television. Paulson said she does not know where she would be without Murphy continuing to give her roles, calling Linda Tripp one of the acting achievements of her life. Their collaboration began with “Nip/Tuck,” after Murphy offered her a part while they were at a social gathering in the backyard of writer Jennifer Salt.

Paulson described herself as feeling like “the right interpreter” for Murphy’s work, saying both she and Murphy are drawn to extremes and high-stakes material.

Other projects and what she is not watching

Paulson also addressed her busy recent schedule, saying she was moving back and forth between shooting the new “American Horror Story” and “All’s Fair.” Asked whether she was playing six characters in the new “American Horror Story,” she named Cordelia, Sally, Venable and Mamie Eisenhower, then said, “It might be five. I can’t remember. It’s a lot!”

She said she was traveling between New York and Los Angeles every seven to eight days while working on both projects, including one week that involved filming “Horror Story” in New York, “All’s Fair” in Los Angeles, then returning to New York for a scene with Jessica Lange.

Paulson also responded to the harsh critical reaction to “All’s Fair,” saying the internet is “the Wild West” and that artists have to protect themselves when putting work into the world. She said she had “the time of my life” on the project and described the group of women involved as “incredibly great,” adding that there is “a ton more comedy” than last year.

As for “Closing Night,” Paulson said making it gave her a creative experience she had not had since playing Linda Tripp, and before that, since “O.J.” She also said she still has not watched “O.J.” and suggested she may not want to see “Closing Night,” because watching her work can lead her to pick it apart.

“For me, they were the most meaningful creative experiences I’ve ever had,” Paulson said, “and I want that to remain true.”