How to recover pin for phone not oassword

I log into my phone with a password and or facial recognition , I go to screen time from settings and I want to add apps that I want all the time, once I section this option I get ask to enter a numeric PIN , which I don’t have or don’t remember entering. My password to log into the phone is a combination or Alph, numeric etc so I know it is requesting something different than my login to the phone. How do I reset this or recover it.