Kaspersky Safe Kids.
It has free and premium features. The premium license is less than $20 a year, and is free to download.
I can block either by certain times, or by usage time. It can be set up to either block completely, or just warn the child. You can either ban certain apps, or ban all but the ones you've whitelisted.
If your child tried to access an app not allowed on their device, it shows up as a "request" on your own device, and you can approve it there.
It's very powerful for its price point, but the UI could use a bit of polish. If you're moderately competent them you can easily figure it all out, though.