The Theme Switcher - Override 🌙 is an updated version of a theme switcher that has been simplified to function as an override, requiring no initial setup. Users can easily incorporate this feature into various elements such as buttons and toggles by simply copying and pasting the code. The default setting for this theme switcher is dark mode, but it can be adjusted to light mode by modifying a single line of code, specifically line 7. This override is designed to operate on live websites, as it does not function in preview mode.