2 reasons why Spider-Man 4 should be a multiversal movie (and 3 it doesn't)
Why it shouldn't: Avengers: Secret Wars is coming either way
Speaking of multiversal movies, it's important to remember Avengers: Doomsday and Avengers: Secret Wars are likely to feature Spider-Man. If that's the case, he'll team up with heroes from different realities to stop a greater evil. So why then would the exact same premise be needed for Spider-Man 4? Why not add a little "palette cleanser" between these two world-ending events? After all, that's exactly what Marvel did by releasing Ant-Man and The Wasp between Avengers: Infinity War and Avengers: Endgame.
Marvel hasn't been able to find a clear direction or even a "big bad" for their Multiversal Saga. It just feels like a collection of disjointed storylines running all in parallel. Sylvie broke the multiverse apart by killing Kang at the end of time... except it was Doctor Strange who broke the multiverse apart by casting a memory-erasing spell to help Peter Parker... except the multiverse was actually broken thanks to a joint effort between Wanda, América Chávez, and Stephen Strange. None of these projects follow the same storyline, so it wouldn't make sense to make things messier by adding Spider-Man 4 into the mix.
Peter should be able to grow as a character before teaming up with other heroes (which will eventually happen in Avengers: Secret Wars either way). Otherwise, we'd just watch him save the day on occasions where he's had external help and that would make him feel a little less spectacular, which is something nobody wants.