Phone is networked locked

This support article has what Apple says about carrier locks: How to unlock your iPhone for use with a different carrier - Apple Support

"Apple can't unlock your iPhone for use with a different carrier. Only your current carrier can unlock your iPhone."

There are potentially two types of locks on an iPhone: one is related to activation with a cellular carrier, the other is an anti-theft measure to prevent use of a stolen or lost phone. The latter can also occur if you failed to enter your phone's passcode too many times.

What we are asking is: Which lock is your phone experiencing? Apple can only provide assistance with how to restore your phone if you forgot your passcode. The other has to be worked out with your cellular provider ... or the cellular provider that it is locked to.

Is this a new iPhone that you purchased directly from Apple or an Apple Authorized Reseller? ... or is it used and you got it from another third-party?

Only a carrier can remove a carrier lock. Apple cannot do that. Are you mistaken in understanding the nature of the lock you are seeing?

Have you tried restoring this phone so that you can sell or give it away?

Ref: What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support