Android 10 brings native support for a system-wide Dark Mode and the same is reflected in the new OxygenOS UI as well. Previously, only a few areas such as the Settings page and a few menus could use Dark Mode. In the new update, most UI elements including the notification shade makes use of the Dark theme.

That being said, there are still areas that do not have a true dark theme such as Digital Wellbeing (in dark grey) and Game Space (white) so you may run into UI inconsistencies here and there. Overall, Dark Mode looks great on the AMOLED display. Besides, most Google apps including Search and GMail have already started to offer a Dark Mode setting, which is great for saving a bit of energy and is also easy on the eyes.