Asked the other day, was it possible to browse using DNS over HTTPS for added security. The only answer is yes.
Open Preferences/Options/Settings (varies with Firefox version) and navigate to the bottom and find Network Settings, then click on the Settings… button.
Scroll down and you will see a checkbox Enable DNS over HTTPS. Check this box and use one of the two presets or custom like me who uses OpenDNS.
Note: Depending on your location on our little planet, some services maybe faster than others. Please test and use the one best for you.
Video on YouTube
Visit my YouTube channel and view the video related to this article: DNS over HTTPS with Firefox.
Other services that can be used other than the presets.