If you want to mess around with bounding boxes and models and stuff, I feel like this script is quite convenient. This lets you set the bounding box of your selected entity, and also let's you see them.
Command Info:
/bb select - Point at your target to select them.
/bb pos1/pos2 - Set the corner locations of the bounding box.
/bb set/reset - Apply the bounding box to your selected NPC, or reset it entirely.
/bb show - Visualize the outline of the...
