Officially, no. The MT6755 variant stopped at Android 6.0 (ColorOS 3.0). However, ported Android 7.1 custom ROMs exist on 4PDA (Russian forum).
For an experienced user, the process is methodical: Oppo F1s Mt6755 Firmware
Always verify the MD5 checksum of your downloaded firmware against community-provided hashes. A single corrupted preloader binary can permanently convert your Oppo F1s into an expensive paperweight. Officially, no