Thanks for your post. There are a couple of results on the Geekbench Browser for the OnePlus 6. At the moment, they are identified as OnePlus A6000 or OnePlus A6003. If you search the benchmark results with one of those three names, you should find them there. (https://browser.geekbench.com/v4/cpu/search?utf8=✓&q=OnePlus+6)
The OnePlus 6 was released fairly recently, so there may not be enough results yet for it to show up in the Benchmark Charts. All of the results on the Geekbench Browser are uploaded by users of Geekbench. The Benchmark Charts are an average of the uploaded user scores for specific devices.
Let me know if there is anything else I can help you with.