I have a tower shaped mesh with a large collision box, which I would like to make smaller than the tower like 10% smaller, so when standing on it, the character would partially go through it (i.e. his feet will be behind the tower).
How do I change the shape, size and or pivot of the static mesh, regardless of the actual mesh size or shape?
I think you meant how to change the shape of the collision box? you can do that by clicking on the collider it in the components list.
If it’s not a mesh you need to move around, you could just disable the tower’s collision and create Blocking Volumes where you need them inside the tower.
To answer your second question, you can change the size and shape when importing the mesh, and the pivot point by dropping it into the world>clicking left mouse button on the move arrows>hold middle mouse button at the same time, then it’ll move the pivot around. After it’s where you want it, you can right click the mesh and go down to the option that says Pivot and set as pivot offset.