how to recover passcode

You don’t.

The passcode only exists on the phone and in your memory.

If you can’t remember it, you have to wipe and restore the phone.

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

From your memory or from wherever you wrote it down (if you did). It is not stored anywhere and therefore cannot be recovered from anywhere.

Which passcode? Phone screen lock passcode? Apple ID passcode/ password?