[Mathnerd314]

MyAnimeList has a pretty good navigation list IMO. For example on https://myanimelist.net/anime/25777/Shingeki_no_Kyojin_Seaso... there is prequel, sequel, other (spinoffs and specials), and "alternate version" (condensed movie summary or remake). Maybe the naming could be better but those relationship types are the basic set for any kind of serialized media. Note that the media type is not fixed, e.g. the sequel to the last (TV) episode of Firefly is Serenity (a movie).

Now it's true that some shows aren't really designed to be serialized, e.g. for the Fate series there is a complicated mess of a graph (https://i.redd.it/6fz5fzz6sfv11.png) and most relationships will have to be encoded as "other", but since it's so messy, almost any watch order is reasonable, so there isn't much structure lost.