Yes, ForeFlight has themes for both light (day) and dark (night). You can set the light and dark app themes to your liking by going to MORE > SETTINGS > LIGHT SETTINGS or DARK SETTINGS. Once you have set up your light and dark themes, there are three app theme buttons that allow you to change between either Light, Dark, or System themes. When System is selected, the theme will automatically follow the iOS system theme selected in Apple Settings.
Image 1. LIGHT, DARK, and SYSTEM themes and settings under MORE > SETTINGS.
Image 2. Light theme setting options.
Image 3. Dark theme setting options.