Android Q was long-rumored to (finally) give us system-level dark mode settings for Android. Based on the current beta, it kind of does, but there's a catch: The setting from Android P which controlled the system-level theme is missing, so the only way that we can find to get it on Android Q is to have it enabled before you flash it — and it's a bit janky when it's enabled.

The Device theme setting (left) on Android P really only changed a few system things (middle), though some apps could pick up on it (right)

For the unfamiliar, Android P had a setting (Settings -> Display -> Advanced -> Device theme) that allowed you to enable a limited dark theme, but it only worked on a few things. Android Q appears to have removed that setting, while simultaneously expanding what it applies to.

Android Q has lost the Device theme setting.

So if you had dark mode enabled via that setting before dirty-flashing the Android Q OTA, it will persist and you'll get to check out the significant expansion of a dark theme throughout Android Q (including some app-specific jank). If you didn't have it enabled, though, then the option to switch to it will be lost to you — at least, until we find another way to toggle it, or Google rolls out a tweak.

Having dark mode enabled seems to break some things in a few apps, as well.

TL;DR: If you want to play with dark mode in Android Q, you'll need to install it over Android P with the setting enabled, and right now there's no way that we've found to turn it off (or on) if you're running Android Q.