TL;DR: Omnipotent beings in fiction aren’t omnipotent because their power extends only over the work they exist in.
Omnipotence is the state or ability of being able to do absolutely anything and everything whatsoever without drawbacks. For example, you could run and fly at the speed of light, lift infinitely heavy things, create and destroy absolutely anything; heck, you could manipulate even logic itself! You could be erased from existence and then just simply recreate yourself from literal non-existence. You could blink so apple-like that Santa in the Speedforce would cry chocolately about it like an elf in Magius. Does that make sense? Absolutely not, but that is omnipotence in essence.
So, in different fictional universes, omnipotent beings can exist. For example, the Presence in DC and the One Above All from Marvel are both omnipotent beings. However, I would argue that they (and every fictional “omnipotent” character for that matter) is actually not omnipotent. This is because omnipotence is the ability to do anything and everything; neither of them would be able to, say, stick their hand of the comic panel they’re in and pull you inside, nor can they affect anything in real life. If you were really omnipotent in real life, you’d be able to casually pull fictional comic and manga characters into real life the same way a magician could pull a rabbit out of their hat.
However, it’s a bit disputable whether omnipotent characters are omnipotent even within their own respective fictional universes, because of a paradox. Now, if you’re omnipotent, you could theoretically create a rock that not even you could lift. However, if not even you could lift it, then you’re, in actuality, not omnipotent. As such, the same could hypothetically apply to fictional omnipotent characters.
However, even if a character is truly 100% omnipotent, the writer is arguably infinitely more powerful than them, since they could always just say the protagonist can punch an omnipotent dude and win anyway because why not and simply leave it at that (or literally anything else).
if you so mighty disprove me without saying “but logic powers!!”
If you can’t, you are unfortunately not omnipotent. ()
Plus, the only options to the paradox would be that they either create a rock they can’t lift or that they can’t create a rock they can’t lift. If they create a rock they can’t lift, then they’re not omnipotent, because they can’t lift it. If they manipulate logic to somehow lift the rock they can’t lift then they’re still not omnipotent if they had to manipulate logic to get around that limit, and the very fact that they had a limit in the first place means they’re not omnipotent.
The fact that they created a rock one could say even the omnipotent being couldn’t lift and be objectively correct about it is proof they’re not omnipotent. Even if they could create a rock they couldn’t lift and lift it anyway, the fact they created one you could describe as being unliftable by them is, again, proof they’re not omnipotent.
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