No one answers because the answer is too simple and only requires math education.
Get the rotation vector and rotate if the vectors mins/maxs are out of the desired bounds.
With blueprints its simply use the (Not Equal) node:
Here is my full blueprint which tells you if an actor is out of the camera’s bounds:
Also you have to use the Set Control Rotation node to set the rotation or your character won’t move? But it depends on your setup!