IIRC you can sign in with an adult iCloud account then set all those same restrictions, protecting them behind an unlock code. The separate child iCloud account

IIRC you can sign in with an adult iCloud account then set all those same restrictions, protecting them behind an unlock code. The separate child iCloud accounts are handy if you do have multiple devices (remote management of those permissions is nice, and app store content sharing is nice) but if you just have a single one for your kid, that's an option. Adult iCloud account, enable restrictions with an unlock code. Unlock it when you need to manage the device or use it yourself. But, IDK, maybe they got rid of that feature. Definitely used to be able to do that.