Do you mean leaking on the LAN or on the Internet? Because the former is a whole different kettle of fish.

Normally, LAN clienta should work with the router and let it organize these things. It's best for example to just let the router advertise itself as DNS and proxy the requests via DoH/DoT, you get a central place where you set the resolver, you can filter ads, you can do caching etc. The router can also intercept (clear) DNS traffic and secure/cache it as needed.