How can I unlock my iPhone 12?

Which One?

If you forgot the passcode on your iPhone, or your iPhone is disabled -

If you forgot your iPhone passcode, use your Mac or PC to reset it - Apple Support

If your phone is carrier locked -

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

If your phone is Activation Locked -

How to remove Activation Lock - Apple Support

What kind of lock?

Unavailable?

Security Locked?

Activation Locked?

Carrier Locked?

Some other kind of lock?