Set Content & Privacy Restrictions

1. Go to Settings and tap Screen Time.
2. Tap Continue, then choose "This is My [Device]" or "This is My Child's [Device]."
   • If you're the parent or guardian of your device and want to prevent another family member from changing your settings, tap Use Screen Time Passcode to create a passcode. Then re-enter the passcode to confirm.
   • If you're setting up Screen Time on your child's device, follow the prompts until you get to Parent Passcode and enter a passcode. Re-enter the passcode to confirm. 
3. Tap Content & Privacy Restrictions. If asked, enter your passcode, then turn on Content & Privacy.

Make sure to choose a passcode that's different from the passcode you use to unlock your device. To change or turn off the passcode on your child's device, tap Settings > Screen Time > [your child's name]. Then tap Change Screen Time Passcode or Turn Off Screen Time Passcode, and authenticate the change with Face ID, Touch ID, or your device passcode.

Taken from Apple's Support Page