Adding a permission system:
- To make your players have to use it, give them the blockhats.usepermissions perm.
- To allow all blocks to be used, give the blockhats.* permission (most likely this is for admins)
- To allow only 1 specific item type to be used, give the blockhats.(itemtype) perm. Example: blockhats.stone will allow players to put stone blocks on their head.

Still works with 1.16 up to latest