If your device is not yet on ColorOS 11, you can check for the final available update through these methods: OPPO Software Update : Step-by Step Guide
The safest way to update your Oppo A9 2020 is via the built-in Over-The-Air (OTA) updater. Oppo A9 2020 Firmware
: When the tool says "Download Complete," your phone will automatically reboot into a fresh version of ColorOS. If your device is not yet on ColorOS
: The tool should show a "Connected" status. Click "Start" and watch the progress bar turn green. but not all
The stock firmware comes with pre-installed apps (Facebook, Amazon, various game centers) and system ads in File Manager, Weather, and App Market. You can disable most, but not all, without ADB commands.