Blender – Copy Bone Constraints

Software:
Blender 2.83

To copy bone constraints from one bone to other bones:

1. In Blender Preferences > Add-ons:
   Find the Interface: Copy Attributes Menu add-on, and enable it.
   
2. In Armature Pose Mode,
   Select one or more bones, and select last the bone that has the constraints you want to copy.
3. Press Ctrl + C to open the Copy Attributes menu, and select Copy Bone Constraints.

Related post:
Quickly setup bone constraints