I want to walk around inside a static mesh like a hamster in a ball. World Transform?

[ClockworkOcean]

Unless you want to write a whole different pawn any physics dimension, it might be easier to distort the level around the player with a post process. This market place product does it

Spherical Shader in Materials - UE Marketplace

Also, this is about it

Part 1: Spherical world - Curved World Shader / Animal Crossing Camera - Unreal Engine 4 Tutorial