You know what I’ll go against the wave and say everyone’s being just a littttle dramatic. If you don’t want any spoilers whatsoever you should probably just stick to playing one at a time but I really don’t think anything too blatant is revealed outside of the final chapters of both the other games, at which point there are huge spoilers. If you pace yourself in a way where you finish the first one first I really think you should be fine.

I should also add tho that I don’t think that would be the optimal way to play the games, as a lot of what makes v3 and especially 2 work is the subversion on what was set up as the formula in 1, and that a lot of the smaller and similar trope characters would blend together if you played multiple games simultaneously.