How can I unlock sim locked

If you want to unlock the iPhone to work with other carriers you will need to speak to the carrier it is locked to. Apple has some info on this here.

You can give your carrier a call and if you meet their requirements, they’ll usually unlock your phone for free, which might take a few days. You can also use tools like Passixer to unlock your SIM. Whichever way you go, just make sure your phone isn’t blacklisted and that it’s fully paid off.