How to update or downgrade(?) a datapack.

Heyo! I'm a pretty big newbie to datapacks and stuff, the most experience I have is making like basic recipies or loottables using online resources, but not any actual experience. Anyway, there's this datapack I've been playing that is super fun, but right now it's only in 1.20.4, so I want to try and update it to 1.21 or downgrade it to 1.20.1, since those both have better mod support and I wanna throw in some mods to the game. How would I go about doing that? The datapack itself is pretty expansive, so I think it might be more difficult than changing the pack format id, but if someone could point me towards like a guide or something that takes you from start to finish that'd be super helpful!