OnePlus
Change Preset Theme on Home and Lock Screen auf OnePlus
The preset theme on a OnePlus phone bundles color accents, brightness behavior, and contrast into a single style applied across the home screen and lock screen. It is not the same as a manual dark mode toggle, since it also changes accent tints used in menus and widgets. If icons look washed out in bright light or widgets are hard to read at night, switching the preset theme often fixes both at once without touching individual app settings.
To change it, open Settings ➔ Customization ➔ Preset Theme. You will see three options: Vibrant tints for stronger color accents, Illuminating light for a brighter overall look, and Nuanced dark for reduced brightness and softer contrast. Tap the style you want, then confirm with Apply.
The change applies system-wide, so app icons, quick settings, and some pre-installed apps update their tint immediately. Third-party apps with their own theme engine are not affected and may need a separate toggle inside the app itself.
If you only want a darker interface without changing accent colors, a separate dark mode toggle under display settings is usually the better fit. Use the preset theme when you want the color accents and brightness to change together.