Oppo
Turn Screen Rotation On or Off auf Oppo
Auto-rotate on Oppo phones uses the built-in position sensor to detect whether you're holding the device upright or sideways. When it's active, the home screen, gallery, browser and most apps switch between portrait and landscape as you turn the phone. When it's off, the display stays locked in whichever orientation it was in when you disabled the feature.
To change it through the system settings, go to Settings ➔ Display & brightness and enable or disable Auto-rotate. The same toggle sits in the quick settings panel, which you open by swiping down from the top of the screen, so you rarely need to dig through the settings menu for a quick change.
When the screen still won't rotate
Some apps request a fixed orientation on purpose, for example video players or certain games, and they'll override Auto-rotate even when it's switched on. If only one app misbehaves, the setting itself is working correctly and the app is the source of the behavior.
Leaving Auto-rotate off is useful if you read a lot in bed or use your phone mounted at an angle, since it stops the screen from flipping accidentally. It has no meaningful effect on battery life, so choose it based on convenience rather than power saving.