A spokesperson confirmed in a Tweet that the company is adding this dark mode in both Gmail and Maps for users of Android and iOS 11. And a user can enable it with a new toggle in the setting panel of Gmail.
As of now, the dark mode options are only available for Android 10+ and iOS 11+ as confirmed in a follow-up tweet. And if these OS versions are available on your phone then you may get a chance to enable this dark mode.
The same option is available in the Maps application. Some Redditors have also spotted minor hints of dark mode in the Maps application with an older OS or device model. Being on the latest iOS version, most of the users will be able to update their application for this dark mode and can explore the new feature which can help you to save give relax to your eyes and battery.
Gmail & Maps App Android Hands-on Review
I am a OnePlus 7 Pro user and I have got the chance to test this out. The battery life has definitely worked long with this dark mode activated while there is a less negative impact on eyes for longer use of these applications.
The easy toggle to stop or resume this dark mode makes it more simple unlike the dark mode introduced by Instagram.