Update codes

To unlock your iPhone, follow the steps described in the Apple article:

(< iOS 15.2) -> If you forgot your iPhone passcode

If you forgot your iPhone passcode - Apple Support

(iOS 15.2 and newer) -> If you see an iPhone or iPad unavailable message or Security Lockout screen

If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

Do you not know your own passcode?

It's the passcode used to unlock your iPhone. You can't get it from anywhere, as only you know it, and its not stored anywhere.