To get Android 7.1.2, users frequently turn to community-developed ROMs.
There is no official 7.1.2 update . Any "7.1.2" firmware found online is likely a Custom ROM (like LineageOS) or an unofficial port. oppo f1s firmware download 712 work
While the F1s officially stopped at Android 6.0 Marshmallow (ColorOS 3), firmware packages allow you to manually update or return to a previous stable version. To get Android 7
: Must be enabled in the "Developer Options" of your phone. To get Android 7.1.2