If you’ve been looking around for parental controls to help manage your kids’ Apple devices, you might want to put on the brakes: The new operating system, iOS 12, has a feature called Screen Time that might have what you’re looking for, and it became available this month.
Screen Time lets you see exactly how much time your kids spend on their phones and tablets, the times of day they’re most active, and which apps they use the most. You can also set app time limits, filter inappropriate content, and schedule “downtime”—basically, shut down the device—whenever you want. (By the way, you can do this for yourself if you need help managing your own device use.)

Below is information from Steve Window – Cyber Safety and Digital Wellbeing Advocate- Anglican Schools Commission

https://www.anglicancsaw.org/2018/09/18/ios12-screen-time/