Turning on the all-screen mode of an OPPO phone usually involves adjusting the settings to maximize screen usage. Here are the general steps, but please note that the specific steps may vary depending on your OPPO phone model and OS version
Open Settings: On your OPPO phone, find and open the Settings app.
Display settings: In the settings menu, look for the "Display" or "Display & Brightness" option and tap to enter.
All-screen setup: In the display settings, look for "Full Screen", "Full Screen", or similar options. This option may be under "More" or "Advanced settings".
Adjust the all-screen options: In the all-screen setup, you may see options such as hiding or showing virtual buttons, adjusting the app's display ratio, and more. Adapt to your needs.
Apply settings in full screen: Here, you can also set which apps can run in full-screen mode. Select the app you want to display in full screen.
Acknowledgment and Exit: When you're done setting up, make sure to save your changes (if needed) and exit the settings menu.
If you're unsure or can't find these options on your phone, it's recommended to check your phone's user manual or visit the official OPPO ** for more information on a specific model. In some cases, you may need to update your operating system to the latest version to access these features.