DarkModeBuddy for macOS enables dark mode based on ambient light levels, using the MacBook’s light sensor, and allows you to set a delay before switching.
I’m not a big fan of dark themes. But early in the morning or when the room is dark, I do prefer it. While switching themes by time is easy, what about switching based on lighting conditions?
On macOS, this can be solved with a free app called DarkModeBuddy – assuming you have a MacBook, since the app relies on the built-in light sensor.

After installing it, you can set a specific light level below which dark mode will be automatically activated. You can also set a delay (in seconds) to prevent the theme from changing if the light is briefly turned on or off.