How to make Step Offset 0 when Character Controller makes contact with certain tag?

I want to prevent the first person player from climbing on certain boxes with the tag "boxes". I have tried to use the OnControllerColliderHit but the controller's step offset does not go to 0. What am I missing?

     private void OnControllerColliderHit(ControllerColliderHit hit)
     {
         Rigidbody body = hit.collider.attachedRigidbody;
         

         if (hit.gameObject.CompareTag("boxes"))
         {
             m_CharacterController.stepOffset = 0f;
         }
         else
         {
             m_CharacterController.stepOffset = 0.18f;
         }
         
     }