Unofficial TWRP for Oppo A91 (CPH2021) running Android 11.
This recovery should work also on the Oppo F15 (CPH2001) as it's a rebranded A91.
https://m.gsmarena.com/oppo_a91-10000.php
- ADB
- MTP
- External SD Card
- Decryption
- OTG (Not yet tested)
Since this phone has fastboot disabled it is necessary to use alternative tools. I recommend using MTKClient.
Just unzip the file and flash the TWRP to the recovery partition.