Apple Maps comes with a feature known as night mode. With it, after a certain point during the day when the sunlight goes down, Maps will enter a lower-light state with darker colors as to be easier on your eyes for night-time navigation.
If you really like night mode, and wish there was a way to keep it enabled 100% of the time (even during the day) then you might be interested in a new free jailbreak tweak called AlwaysNightMode.