Open Settings
Tap Display & Brightness
Under Appearance, select Dark
Turn on Automatic if you want Dark Mode to switch by schedule
Open an app and check if it supports Dark Mode
In supported apps, look for a theme or appearance setting inside the app
If an app does not support Dark Mode, use Smart Invert
Open Settings
Tap Accessibility
Tap Display & Text Size
Turn on Smart Invert
Use Dark Mode-compatible wallpapers and app settings where available