Here is the part most "exclusive ROM" sellers won't tell you. Oppo devices from this era (R11 series) have with no official unlock method.
6.01-inch AMOLED capacitive touchscreen, 1080 x 2160 pixels (401 ppi density). oppo r11st global rom exclusive
However, users outside of China frequently encounter severe software limitations with the native Chinese firmware. The lack of pre-installed Google services, aggressive background app restrictions, and persistent Chinese bloatware drastically diminish the user experience. Here is the part most "exclusive ROM" sellers won't tell you