Simply triggers. Create blueprint inherited from trigger or empty blueprint. In second case add some primitive that will check for player pawn. When event OnComponentOverlap (primitive) is triggered you need to cast Other actor to your pawn class (where fixed Z code is) and change it’s CameraHeight variable to what specified in your trigger as another variable (let’s call it Camera Desired Height). You can put any amount of triggers and from inside level editor change their Camera Desired Heights to what needed in different places.
If you want disable Z fix than you need to create boolean variable to use it as switch. You need a Brunch (blueprint node) by this bool where on False Target Offset needs to be zero vector (set to 0,0,0) and on True use Z-fixing. Enabling/disabling is similar to above with triggers.