New certifications pertaining to a device called the OPPO CPH1931 have allegedly been found online. This device as described is a phone with a 6.1-inch screen and a 5000mAh battery. Its most interesting attribute so far may be references to the recently-released CPU, the SM6125, or Snapdragon 665.
https://www.notebookcheck.net/OPPO-might-be-the-next-OEM-to-release-a-phone-based-on-the-new-Snapdragon-665-SoC.427300.0.html