To address the core question directly: there is no official Android 11 update available for the Oppo F1s. When the F1s was launched, it shipped with Android 5.1 Lollipop (or Android 6.0 Marshmallow depending on the region). Oppo provided updates up to Android 6.0 Marshmallow for most variants via their ColorOS skin. However, smartphone manufacturers typically support devices for two to three years. As the Oppo F1s is now several generations old, it has reached its "End of Life" (EOL) status regarding software support. The hardware architecture of the F1s—specifically the MediaTek MT6750 processor and the limited RAM configurations—was optimized for the software ecosystem of 2016, making it ill-equipped to handle the resource-intensive architecture of Android 11.
Would you like steps to check your current software version or backup data instead? oppo f1s android 11 update download
If you are an advanced user willing to void your warranty and risk bricking your phone, you can look for (Android 11) builds for the OPPO F1s (A1601) . To address the core question directly: there is