Get Current Dimension Player Is In?

I am making a mod that needs to do something if the player is in the overworld, to make sure they can go super high in the sky!

But the only problem is, I can't figure out how to detect if the player is in the overworld, and not in the nether, end, or any other dimension from any other mod.

Is this even possible? If so, how would I do it, and if not, what could I do instead?

Any help would be greatly appreciated!