If you go into edge://flags/ you can enable 'Force Dark Mode for Web Contents' and get the same effect the Dark Reader extension gives you. Also when you click the drop down menu to enable it you'll notice there are six other inversion settings so you can set your preference. Select the Dark Theme in settings for the full browser effect. You don't always need extensions/add-ons, sometimes the browser has the capability to do more than people realise, with a bit of tweaking.
Also worth noting from the link that Panzer posted about the Dark Reader extension;
"
The developer says similar attacks taken place and affected Chrome, Edge, and Firefox users" ...
Edge Stable updated to Version 81.0.416.77;
https://docs.microsoft.com/en-us/dep...1041677-may-18