As far as displays of power go, sky splitting seems to be more of a Yonko/Great Pirate thing.
For Akainu and the other Marine powerhouses, I expect giant shockwaves (Harald v Xebec, Kuzan v Garp, probably whatever caused the big hole in PH) as well as super terraforming (like in PH/Wano, maybe Ennies Lobby if the permanent daylight was due to Kizaru)
But, you know, it's Oda so whatever can happen.