Editing Physics Asset Physics Bodies
Editing Physics Asset Constraints
Right-click an already existing Physics Body or a Bone in the Hierarchy Panel.
Select the type of Physics Body you wish to add from the Context Menu using the left mouse button.
If the Bone in the Hierarchy Panel does not already have a Physics Body on it, the only option in the right-click context menu is "Add Body."
Finally, you can just double-click a bone that does not have a Physics Body in the Hierarchy Panel to "Add Body."