Automatic Dark Mode
As of Mojave, macOS already has Dark Mode baked-in. But there’s one critical feature missing from the easier-on-the-eyes theme. Namely, you have to toggle Dark Mode manually.
That’s changed in macOS Catalina. In addition to permanent Light and Dark themes, there’s also a new “Auto” theme in the System Preferences > General menu. Selecting this will automatically change your Mac from Light mode to Dark mode depending on the time of day.