Open the Settings app
Tap Accessibility
Tap Display & Text Size
Turn on Smart Invert
Or turn on Classic Invert
To make the whole interface darker, go to Settings
Tap Display & Brightness
Select Dark
Turn on Automatic to schedule Dark Mode
For supported apps, open the app’s settings and enable its dark theme
Use Control Center to quickly toggle Dark Mode if available
Enable Reduce White Point in Accessibility for darker-looking screens
Lower screen brightness if needed