Unity Third Person Script - Help

Alright, I'll go over a few ways you can do this, so pick whichever one works best for how you built the game. You can use a NavMash to chooses 'areas' such as places where you might need to crouch, and then have a script that makes your character crouch whenever hes in those areas. This would work best for static maps, and if you don't mind setting it up for all of your maps. Another way would be to have a 'double' collision box system. The bottom one would work just like you currently have it, and the top one would activate crouching. More specifically: the top box would represent the difference in height your character has when crouching. So if anything touches the top box but not the lower one, they crouch to pass through. Just make the top box a bit smaller so it doesn't crouch if it runs in to just any wall ya know. If you use projectiles and need the entire hitbox, make sure you deactivate detection on the top box if the player is crouching! A final way would be to use a short Raycast from close to the top of their head, and if it hits something then crouch. That's basically the same as a hitbox though. These last two methods work on all types of maps, but the first one only works on static maps, and really you should only use it if you already have a navmesh set up.

Secondly, stairs work the same as the navmesh described above. set a zone for stairs and have a script do the rest if in those areas. Otherwise, you can tag the hitboxes for the stairs as "stairs", and use in your script, if the player is therefor waling on a hitbox tagged 'stairs', have the script run a "look up" code. Either way looking up and down would be tough, because that doesn't detect if the player is going up or down the stairs. I'll leave that part to you! (Maybe have a hitbox in front of the player and check if that collides with the stairs. If he is going down, it'll be in the air and wont collide.