i have two bad examples both on the N64:
Perfect Dark has a “Counter-Operative” mode for the campaign, where the second player is a random guard somewhere in the level and has to kill the first player before they beat the stage. If they die, then they get yeeted into a totally different guard. So in that way, I think you can play as all the “characters” in the game…but they’re all identical? maybe?
Banjo Tooie has a mode called “Bottles’ Revenge” that is not accessible except with cheat codes/hacking. It’s literally the exact same thing though - a second player possesses any enemy in the game and tries to kill the first player. I like to think this is what inspired Mario Odyssey.
Anyway a better, real answer to this is probably PixelShips which is a side-scrolling shmup where you can collect every enemy ship and play as them. Cool game.