OnePlus
Start the Screen Saver Manually auf OnePlus
OnePlus phones tie the screen saver to the Display settings, but the system only launches it on its own once the phone is charging or resting in a dock. If you just want to check how a photo slideshow, the clock face, or a colour palette looks, waiting for that trigger is not necessary.
Open Settings ➔ Display ➔ Screen saver ➔ Start now to launch the feature immediately, regardless of the charging state. The same menu lists the available screen saver styles, so you can switch between the current time, a colour palette, or your own photos before testing it.
Starting it manually helps when you are setting up a custom photo album or checking a display style at night, since you see the result right away instead of connecting a charger first. If nothing appears even after tapping Start now, check the toggle at the top of the same screen - if the screen saver feature itself is switched off, the preview is skipped.
Manual activation does not change how the screen saver behaves automatically afterwards. It only opens a preview session that ends the same way as the automatic version, either on touch or a button press.