Yes, but only via full OFP flash. OTA downgrades are blocked. Backup data first – downgrading triggers a full wipe.
In simple terms, firmware is the low-level software programmed into the read-only memory (ROM) of your device. For the Oppo A9 2020, this includes the Android operating system (ColorOS), kernel, drivers, and the modem (radio) software. Oppo A9 2020 Firmware
The device saw several major transitions during its support lifecycle: ColorOS 6.1 (Android 9). Yes, but only via full OFP flash
The A9 2020 debuted with , which focused heavily on maximizing the utility of its Snapdragon 665 chipset. Oppo A9 2020 Firmware