Would Captain Marvel 2 Be Set Before Or After Endgame?
While Captain Marvel's '90s setting was mainly for the purposes of telling Carol's origin story and retconning her into the MCU, that doesn't necessarily mean that a sequel would be set after the events of Avengers: Endgame. The end of the movie sees Carol jetting off on a brand new mission that will take her on an adventure through space, and it would be a shame if we never got to see what happened on that mission. Captain Marvel 2 may take a similar approach to Wonder Woman 1984, which is also a prequel to the main events of its cinematic universe, and tells a story that's still set in the past, but with a more recent time setting than the first movie.
What Captain Marvel 2's Story Could Be
Warning: SPOILERS ahead for Captain Marvel
If Captain Marvel 2 is set in the past, in the immediate aftermath of the first movie, the story could simply be about Carol's mission to find a new home for the Skrulls, where they can be safe from the tyranny of the Kree Empire. This would be a neat way to bring back Ben Mendelsohn's Talos for the sequel, especially since his performance was one of the most widely-praised aspects of the first movie. Escorting the Skrulls across the galaxy is a compelling cause that audiences are already invested in, and Carol could get into all sorts of misadventures along the way - perhaps even meeting younger versions of Yondu and Peter Quill, or the other Guardians of the Galaxy.
Interestingly, returning Guardians of the Galaxy villain Ronan the Accuser departs Earth with an ominous threat that he and the other Accusers will one day return to collect "the weapon" (a.k.a. Carol) - a threat that can't really be paid off if Captain Marvel 2 is set post-Guardians of the Galaxy. If it is set in the past then Captain Marvel 2 could bring back Ronan as the main villain... but that seems unlikely. He's not one of the MCU's stronger antagonists, and we've already seen him defeated twice. Another possibility is that Captain Marvel 2 could bring back Jude Law's Yon-Rogg, but given the satisfying conclusion to his and Carol's arc, the sequel is probably better off introducing a new threat.
Related: Captain Marvel's Ending Explained
Captain Marvel Sets Up Spectrum For The Sequel
If Captain Marvel 2 is set a significant period of time in the future, there's a strong likelihood that Monica Rambeau (Akira Akbar), daughter of Carol's best friend, Maria Rambeau (Lashana Lynch), will return as an adult with superpowers of her own. In the comics, Monica gains superpowers and currently goes by the superhero moniker Spectrum, with the ability to convert her body into pure energy. Captain Marvel spends a considerable amount of time fleshing out young Monica's fearlessness (she encourages Maria to accompany Carol on a dangerous mission) and her own desire to become a hero one day, and she even inspires the colors for Carol's Captain Marvel costume. Monica is 11 in 1995 and therefore would be in her 30s in the present-day MCU - around the same age as the rest of the Avengers. We'd be surprised if "Lieutenant Trouble" didn't return in Captain Marvel 2.