Easiest way is to hold down "alt" on startup. If you have a firmware password, it will display a padlock.
https://community.jamf.com/t5/jamf-pro/how-can-i-tell-if-my-macbook-pro-has-a-firmware-password/m-p/209116
Jamf Nation
Hi, Can we add the command to set a password if result is Not set ?