Gmail has announced Dark Theme for Gmail for both iOS and Android.
If you own an older version of the app, you might need to change the settings manually.
Turn on Dark Theme in Gmail
- Open Gmail.
- Click the Hamburger icon on the top left.
- Scroll down till you find Settings.
- Click on settings and then general settings.
- Select the theme and choose the dark mode.
This mentioned step is for older versions.
If you’re a google pixel user, you will have this feature as it will automatically turn it on when your phone goes on battery saving. While iOS and Android users have to wait 15 days to get it.