How do I prevent a child's iPhone from enabling Hotspot despite Family Screen Time settings?

This seems to have been asked a lot and there is no go answer. The ability to block the option to turn on/off Hotspot on a child's iPhone either doesn't exist, or the provided instructions do not work. Instructions I've seen are to go through the screen time settings, go to content & privacy, and change Cellular to "do not allow." This does nothing to the child's device. All the settings are able to be accessible and changed, both in the hotspot section as well as the general cellular section. Typical behavior for other settings set to "do not allow" either grey out the section altogether or require a screen time pin to adjust, and neither happens in this situation. This should 100% be an option to disallow or at minimum control through a time setting.

I've also attempted to contact my carrier to see if it can be turned off at their end, & all they know to do is to provide the specific settings on the iphone itself about how to turn off hotspot. Which again, does not help because the child is able to turn on the setting without restriction.

[Re-Titled by Moderator]