The rear camera of OnePlus 6 is 16+20 MP Dual camera setup. It has a portrait mode and Optical Image Stabilization. The 16 MP Camera comes with Sony IMX519 sensor with 1.7 aperture which enables OIS, and 20 MP Camera comes with Sony IM376K sensor and same 1.7 aperture. I didn’t get the use of this secondary sensor here because it is at the same aperture and focal length as the first sensor and also it is not even a telephoto lens which is quite confusing. Well, on the front, you get 16 Megapixel Camera with f 2.0 aperture and EIS. And the portrait mode is available on both the side. Front as well as the rear.
Here are some camera samples of OnePlus 6 we took in a daylight. The photos are looking quite good here. The portrait mode detects edge perfectly.