Hello,
The issue you’re having could probably be because the PIVOT POINT of the character is in the middle of the the mesh. So, if you set the Z scale to be 1.5, you get 1.5Z in one direction and 1.5Z in the other.
I would use the MODELING MODE to move the pivot point to the bottom of the cube so all Z transformation happens in one direction.
This is, of course, assuming I’m interpreting what you mean correctly. Your needs are still a little vague to me.