How to recover an iPhone 12 mini with forgotten PIN and separate Apple Account?

You say, "the iCloud owner is n*****@icloud.com, which does not mean much to me," but then say, "I am the rightful owner of the iCloud account." The two statements kind of contradict each other in terms of not recognizing an iCloud address which you claim belongs to you.

Note that there is a difference between a PIN (passcode) and an Apple Accccount password. Phil0124's post presumes you have forgotten your account password. If you have forgotten the PIN, read this article If you forgot your iPhone passcode or your iPhone is disabled - Apple Support If you have forgotten you account password, read this article: If you forgot your Apple Account password - Apple Support

If the account does not belong to you, or you cannot get access to all the information, then you will need to ask Apple to reset the iPhone. Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Read the requirements and steps for an Activation Lock support request at: https://al-support.apple.com/#/additional-support and links at the bottom right for the type of service requested. Apple says they may require "proof of purchase documentation” and that you need “proof of ownership documentation”, but does not detail what currently constitutes proof other than it “must include the product serial number, IMEI or MEID.” User reports on this community indicate that typically Apple will ONLY accept an original receipt issued by Apple or an Apple Authorized Reseller. Presumably this is the only kind Apple can authenticate against fraud since Apple is not involved in third party sales. Apple recommends that you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support

If Apple resets the device this will give you access to the device but won't restore access to the account used to lock it. There is nothing that can be done to expedite an Activation Lock request.

Hello,

This is a user to user forum, you are not addressing Apple Support here. Because of that fact we cannot actually unlock the account for you here.

You can review the following support documents to get access to the Apple Account and by extension the iPhone 12 mini.

click here ➜ If you forgot your Apple Account primary email address or phone number - Apple Support

click here ➜ If you forgot your Apple Account password - Apple Support

click here ➜ How to remove Activation Lock - Apple Support

There is a link to contact Apple support directly at the bottom of the last support document linked above to directly request removal of Activation Lock which seems what you are after. Apple support will request an original receipt or proof of purchase from Apple or an Apple Authorized reseller before they can unlock the device for you.