How to script a charcter inside of a model when spawning

Hi guys! My team and I are currently working on a new sick game!
In this game, the player needs to be inside a model as the character. So that model could actually move etc. But we don’t really know how to do so. Can any of you guys help us?

(If it is possible, we want the player to change models from inventory. Hopefully that can be taken into account.).

Reference: [WORLD 2] UFO Universe - Roblox. In this game, the user is inside of an UFO.

Thanks in advance!