How Do I Turn on Find My on My Child’s Device?

This is very straight forward if Account Changes has not been locked in Screen Time.

 From your child’s phone:

• Go to Settings > tap on your child’s profile
• Tap on Find My
• Tap Find My iPad 
• Toggle on Find My iPhone/iPad, Enable Offline Finding and Send Last Location

If Account Changes has been locked (your child’s profile is greyed out), you will need to unlock this first.

 From your phone:

• Go to Settings > Screen Time > select Your Child
• Tap on Content & Privacy Restrictions
• Tap Account Changes and select Allow

Next, follow the instructions above and remember to re-lock the Account Changes setting once Find My iPhone has been activated.