Maybe it's a dumb question but will I get any trouble for messing with the anti cheat to play?
Not a dumb question at all.
Generally speaking:
Disabling EAC (since that was the specific anti-cheat under discussion)
should disable any online components as well. Which is good, because you don't want to be online with a game state out of line with the dev's expectations.
- Obviously, so long as you
never go back online after disabling EAC (you'll probably need to reactivate EAC for that), no trouble at all can occur, no matter how heavily you cheat or mod the game.
- So long as you did
not cheat or mod in solo play, reactivating EAC and going back online after the fact should not cause any trouble.
- IF you mod the game AND go back online eventually afterwards, THEN the dev can download your save / gamestate / stats, see something out of line, and ban you from multiplayer or whatever penalty applies for your game. That's how it works for Elden Ring. If you don't know exactly what they look for, and you can't, because that code is entirely server-side, you can't be sure whether you're safe.
To avoid that potential issue, in that last scenario you want to wipe your saves/profile before going back online, so there is no trace of your modding / cheating.
Games where MP is a separate component from SP
probably don't look at your solo saves at all. Elden Ring mixes the two, but that's the exception rather than the rule.