You don't, you need to backup before your phone becomes locked.
To unlock your phone, you will need to reset it. Unfortunately your data is already gone.
If you forgot the passcode on your iPhone, or your iPhone is disabled or unavailable -
Click on the link for instructions on how to reset your passcode without a computer if you have iOS 15.2 or higher.
How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support
Click on the link for instructions on how to reset your passcode using a computer.
If you forgot your iPhone passcode - Apple Support If you forgot your iPhone passcode - Apple Support