quarantine 'em

The film "The Matrix" is a tremendous example of this concept in practice. The film shows a single, finite story in what is very clearly a significantly larger universe

Other parts of the universe, not crucial to the story, are mentioned but not shown: ships other than the Nebuchadnezzar, the city of Zion. Obvious questions are raised but left unanswered because they strictly don't need to be, like: WHY is Neo?

(And despite all of this there's still a whole bunch of worldbuilding and exposition in The Matrix. Think of any long conversation between Neo and Morpheus, particularly the first Construct scene. But the exposition is EXECUTED compellingly)

The Matrix presents a heavyweight universe with a lot of moving parts. Less than half of it is actually demonstrated in that first film, but... as viewers, we get the impression that if we asked the follow-up questions, there would be good answers

And those answers are not required to support the stripped-back story. We don't need to see either the beginning or the conclusion of the machine war. Neo's story is sufficient, it opens, it closes, DONE

But then we get the sequels... Dissecting the sequels is a BIG job. No single thing went wrong there. But they seemed more excited about exploring more of the Matrix universe than about telling the next story

Nowhere is this clearer than in the Architect scene. Here, we learn that Neo exists to encapsulate the errors introduced by the human need for free will/choice, and that he is part of a repeating cycle of destruction/recreation. He then CHOOSES to break that cycle, ending the war

This basic concept is SOLID. This is the core of a single, solid movie. Act one: Neo has questions: why does he exist, and why is the war not over? Act two: Neo finds out he is part of a repeating destructive cycle. Act three: he breaks it