You can restrict System Settings > Accessibility. At least JAMF has the option in the configuration profile, but it may have been broken with Ventura and JAMFs love of tech debt has not removed it yet.
For your configuration profile, check the location of the plist you are changing. Just because the domain exists, does not mean it can be managed.
- Non-managed stuff goes in /Library/Preferences, or /User/{userID}/Library/Preferences.
- Managed preferences go in /Library/Managed Preferences and /Library/Managed Preferences/{userID} for MDM enabled users.
- Not all domains are configured to respect /Library/Managed Preferences.
In the likelihood this cannot be managed the best you could do is package your plist and push it overriding the existing plist on the device. It would not be managed, and a crafty user could just delete the plist but until they do that the Mac should behave as you expect. Apple has a pretty strong history of not allowing management over things they feel users should control. This seems like it would fit the bill of something apple would feel should be under user control.
