We already know that Gmail and other Google apps are set to get dark mode in Android 10. The rollout for Gmail has started, but unlike many of Google's Android apps that adopt the dark theme from the overall settings, you'll need to turn it on within Gmail.
Here's how to do that:
- Head into the Gmail app on your phone. Tap on the hamburger menu in the top left corner of Gmail.
- Scroll to the bottom of the list to get to Settings.
- Select General Settings.
- Tap on Theme at the top of that list.
- Select Dark. Or if you've set the dark mode as the system default, select System default.
Source: CNET