Restrict SSID that wifi can connect to

I find it interesting that this doesn't come up more because I know this is a constant issue with parents in my childrens' school.

How can I prevent my children from connecting to non-approved SSIDs? I.e. how to set up SSID whitelisting?

This is a serious issue because parents can implement only so many controls via Screentime and the rest needs to be implemented by parental controls on their home wifi (router, etc.). Children can bypass these parental controls simply by connecting to another wifi network/hotspot. It seems to me a very basic expectation that I should be able to whitelist which SSIDs their iPad can connect to. But I haven't been able to find where this is, if it exists.

Am I missing something here? I know plenty of parents are concerned about this because I've heard them talk about it. But I find the lack of posts about this during my web searches very bizarre. So coming straight to the source here in this support forum.