How to Manage your app usage
Set quality time
In Settings > Screen Time, turn on Downtime. Only apps you add in Screen Time > Always Allowed can be used between the hours you set — this applies to all devices signed in to your iCloud account with Downtime active.
Limit app category
In Settings > Screen Time > App Limits, tap Add Limit. Tap as many categories as you want, then tap Add and set a daily limit for them. If Block At End Of Limit is off, the limit is soft; it can be overridden without a passcode.
Override apps
You may want some of your apps to override the limit — WhatsApp and Skype, say. Go to Settings > Screen Time > Always Allowed. Phone, Messages and FaceTime are here by default. Add any others you want.