Why are we all talking like corporate copyright lawyers or marketing ghouls, using these explicitly commercial terms 
I'm disappointed by the ease at which "IP" rolls off my tongue. I mean, most of the fiction and entertainment we surround ourselves with are more soulless corporate slop than art, but still
All Final Fantasy games share certain elements but they don't generally take place in the same universe outside of rare cross-over games. I feel like the word universe also places too much emphasis on fictional continuity, whereas the words IP or franchise can encompass anything made under that umbrella even they are entirely separate narratively
I also thought about the word "series" but that's also kind of limited in its scope. I wouldn't call all the Resident Evil games a single series of games, for example. There are the main numbered titles but you also have a bazillion spinoffs with different game mechanics as well as remakes of existing titles and they all influence each other
True yeah people go a bit nuts like trying to explain how Bloodborne and Elden Ring share a universe because of the arcane stat and some art assets and
actually fromsoft might do it
please from soft
do something
anything
People use series and sub-series or side-series for stuff like that. I think it works.