I forgot my screen time password
How to turn off screen time if I forgot my password and don’t want to reset Iphone?
iPhone XR
Question marked as
Click on the link to read what to do "If you forgot the [restrictions or ScreenTime passcode] for your iPhone, iPad, or iPod touch, or your device is disabled" - http://support.apple.com/HT204306 - You can restore from a backup but that backup has to date from before you set the restrictions/Screen Time passcode.
You have no choice. You will have to reset the phone.