My I phone 11 is locked. I need to unlock the phone to switch to another carrier. My current carrier said that only the Apple Store can unlock my phone. Can you help me??

Whoever told you that was misinformed.

ONLY the carrier it is locked to can unlock it for use on other carriers.

How to unlock your iPhone for use with a different carrier - Apple Support

Only the carrier can unlock a phone. Apple is not a carrier.

Whoever told you that Apple could unlock the phone either did not know what they were talking about, or they were simply trying to get rid of you as quickly as possible.