[SOLVED]Making a secret place with collision after entering it

Hello folks, I'm making a 3D maze escape game, I want to add a feature in my game, which you can walk through a wall once (some of the walls in the maze only) to find a secret place, like such in mario where you can crouch and enter some caves you know, but from outside it is same looking with others, how can I do such thing? Thanks

Visualization for you, GAME IS 3D

 

Put a collider on your wall, but set it to be inactive. Have a trigger volume inside of your secret room that when you enter the room, it switches the active state of the wall collider.