He can jump from a building.
since Wano started I always had this theory that the last portion of the Kaido fight will happen in the flower capital/near it cause Wano citizens need to clearly see Kaido defeat with their own eyes after being under his tyranny for over twenty years. But assuming Momo is successful and Onighima doesn't crash , some characters will have to go down for that to happen.
I'm not making the claim Zoro actually fell from Onigashima, as maybe he just fell on floor below/someone caught him but in case he actually fell in Wano I will get more confident in my theory