How much is price of the service?

milijanazmuric wrote:

Message showing Uknown Part for Camera on my Iphone 12pro

That depends on your warranty/AppleCare+ status and where you are located. Here is a link where you can get a repair price quote→Apple - Support - Service Answer Center

If the camera was replaced by an unauthorized service provider, it is unlikely that Apple will now service the phone. The warning will remain forever to alert any other person who may own the phone that an unauthorized part has been installed.

If the phone has never been serviced, then Apple will give you an estimate on repair. The price to replace the rear camera for your phone is $199 in the US.

iPhone Repair & Service - Apple Support