Firmware password is found where
Firmware pass word can be found where
MacBook Pro 13″, macOS 10.13
Question marked as
It can't be found. If it could be found that would kind of defeat the utility of firmware passwords.
From: Set a firmware password on your Mac - Apple Support
"If you forgot your firmware password
If you can't remember your firmware password, schedule an in-person service appointment with an Apple Store or Apple Authorized Service Provider. Bring your Mac to the appointment, and bring your original receipt or invoice as proof of purchase."