One of the new features in the newest update for ChromeOS is the ability to switch between dark and light themes. Dark mode settings popped up more in other products after it was hidden behind developer flags.
The new dark theme would make it easier to read at night or in low light, and the change to a light theme would make things brighter. The only way to look at your screen in dim light is to change the screen tint.
The color scheme of the OS can be shifted between light and dark depending on the time of day, with matching wallpaper options that can subtly change along with it.
There is a way to change your display theme.
The Wallpaper & Style settings can be accessed through your home screen if you press your touchpad with two fingers.