How to disable DoH and DoT network-wide for Apple iOS and macOS

I am running an the Open Source OpenWrt router firmware and wish to disable DoH and DoT for the whole network. In my network lots of latest iOS and macOS devices.

To disable DoH for Firefox is used this guide Canary domain – I search for a similar solution for Apple based devices.

Operating systems Apple

Apple’s iOS 14 and macOS 11 will support both DNS over HTTPS and DNS
over TLS (DoT) when they are released in the fall of 2020.