Any ideas on how to make hollow earth

Im trnna make a hollow earth like in the film GODZILLA VS KONG where there is a world with inverted gravity and you walk on the celing and on the ground. like you can jump up and gravity will reverse. i also want to be able to travel to said area. example lets say i feel in a hole to it from normal earth (surface) How Would i go about doing that?
new to unreal trnna take baby steps and learn this stuff.

There was a plugin, that was able to alter gravity direction, and which zone is affected by which gravity. If it is not able to pull it off, then it should at least give you an idea, how to build it.

Custom movement using the Normal as the basis for it may be better if possibly unpredictable.

You would have to set it up to only look up specific things or alter based on a calculation of some sort related to position within a sphere.

Since it’s a core gameplay aspect it’s probably worth it to axe the existing movement component in lieu of something specifically built for your needs…