How to unlock my iPhone 8 plus to use with another carrier? My phone is paid in full>

If you purchased your iPhone directly from Apple and paid for it in full at the time of Purchase then your iPhone is already unlocked.

If you purchased your iPhone and were paying for it in installments (until paid in full) with a carrier and then your carrier has to unlock it so that you can use your iPhone with another carrier. If this is the case, then contact your carrier and ask for the requirements to get your iPhone unlocked. It is a relatively easy process with most carriers.

Axel F.