If your phone is paid for, and your are out of contract, an you are in the US, your carrier must allow you to unlock your phone in regards to carrier locks. This is a requirement from the CTIA Consumer Code for Wireless Service that all major providers in the US are a signature.

see : https://www.fcc.gov/consumers/guides/cell-phone-unlocking-fa...

Will they make it hard, probably, but at the end of the day, they will comply.

They will not unlock Bootloaders and there are no laws to require them to, and the FCC doesn't have authority over this element of phones.