

This should work, but I have not tested it out and it may not work in future if iOS changes in ways that cause flaws in this approach. Then the iPhone user should not be able to use Personal Hotspot. the iPhone is supervised and the "Allow modifying Personal Hotpot settings" policy has been properly set to disallowed.that changing account settings is disabled on the iPhone.the Apple ID is not part of an approved Family Sharing group of the iPhone user.the Apple ID of the iPhone is not under the control of the iPhone user.So this means that in order to completely disable the usage of Personal Hotspot it would be necessary (as far as I'm aware) to ensure that:

The article says " When is off, only iCloud-connected devices can connect and approved Family Sharing group members may use it, if any.". So you can lock "Allow Others to Join" as off, but it's not that simple to prevent all possible Hotspot usage. The problem is that, as highlighted in this article, you can't outright turn off Personal Hotspot in iOS 13.1 and later. If you open a recent version of Apple Configurator 2, create a new profile, go to the Restrictions section (click "Configure") and scroll down you will find " Allow modifying Personal Hotspot settings (supervised only)". As of Apple Configurator 2.9 there is a new relevant configuration option (only for supervised devices).
