Yes, "X-Men: Dark Phoenix," released in 2019, is considered the last film in the main X-Men series produced by 20th Century Fox. The film concluded the storyline of the X-Men characters that had been developed over nearly two decades. Following Disney's acquisition of Fox, the future of the X-Men franchise is expected to be integrated into the Marvel Cinematic Universe (MCU), but "Dark Phoenix" marks the end of the Fox era of X-Men films.

"X-Men: Dark Phoenix," released in 2019, was generally considered a box office flop. It grossed around $252 million worldwide against a production budget of approximately $200 million, which did not account for marketing costs. Critically, the film received mixed to negative reviews, with many fans and critics citing issues with its storyline and character development. Overall, it struggled to resonate with audiences and did not meet the expectations set by earlier entries in the X-Men franchise.

"X-Men: Dark Phoenix" centers around Jean Grey's transformation into the Dark Phoenix after she absorbs a powerful cosmic force during a rescue mission in space. The film explores themes of identity, power, and the struggle between good and evil as Jean grapples with her newfound abilities, leading to conflict within the X-Men. The central point of the movie is Jean's internal battle and the impact of her powers on her relationships with her friends and family, ultimately questioning the nature of heroism and the consequences of unchecked power.

After "X-Men: Dark Phoenix," which was released in 2019, the next film in the X-Men franchise is "The New Mutants." Released in 2020, "The New Mutants" is a spin-off that focuses on a group of young mutants held in a secret facility, exploring their powers while trying to escape. The film takes a different tone from the main X-Men series, incorporating horror elements into the superhero genre.