OPPO does not publicly host firmware for users. You must rely on third-party firmware repositories. Always scan downloaded .zip or .ofp files with antivirus software.
Here is helpful content regarding the (Stock Firmware).
Qualcomm USB Drivers: Necessary for your computer to recognize the phone in "EDL Mode." Step-by-Step Guide to Flashing Oppo CPH1933 Follow these steps carefully to flash your device:
Correct Drivers: Install the Qualcomm USB Drivers on your PC, as the CPH1933 is powered by a Snapdragon chipset.
Unbricking: If a previous software modification went wrong and the device is now unresponsive.
Device Not Detected: Try a different USB port (preferably USB 2.0) or a different cable. Ensure you are holding the volume buttons correctly when plugging it in.
Before diving into the technicalities of flashing, it is important to identify the device. The model number corresponds to the Oppo F11 Pro , a mid-range smartphone released in 2019 that gained massive popularity due to its pop-up selfie camera and gradient finish.