How can I get dark mode on Safari?

Many parts of iOS can convert to dark mode automatically at sunset and switch back to normal mode in the morning. These settings are available under Settings -> Display & Brightness. In fact, scheduling system-wide dark mode has been available since iOS 13. One app that has been left out, however is Safari.

Using iOS 15 or later and the Safari extension Noir - Dark Mode for Safari, this problem can be solved for $2.99. Noir converts all webpages to dark mode, with a black background and white text. The extension also dims most images.