Chromium-based browsers, including Chromium, Google Chrome, Brave, and others have a native dark mode stylesheet that can be enabled in chrome://flags/#enable-force-dark

It works to varying degrees of success depending on the site. Some sites become unreadable with it.

What I personally do is I have this flag enabled in my primary browser on my main computer, Brave on a MacBook Pro. And for any site that is severely broken I either skip that site, or if the site is important then I open the page in question in my secondary browser, Safari, and read it with its normal default style.