Blacklisted iPhone 13 pro max

blacklisting is something your carrier and carriers in your country handles even if this was not a user helping other users forum and a direct line to apple then apple could not help you, try calling your carrier, though I hear getting an IMEI unblacklisted is pretty hard in many countries

If it’s truly your iPhone and that was previously lost or stolen and has been recovered, contact your carrier and get it unblocked.

If this iPhone a used phone acquired as part of what was likely involving a likely a fraudulent sale somewhere, nobody here can help you unblock it other than the owner of record (not you) and the carrier they were using; it’s considered lost or stolen. Carriers aren’t going to help with these, either.