If you want to improve the low-light photography capabilities of your OnePlus 6, you can definitely improve the low-light performance by using the latest Pixel 3 Camera app(modded version). In my testing, the Pixel 3 Camera app improved low-light photos drastically enough where OnePlus 6 now can take photos with much more clarity, better colors, and most importantly, without noise. Google has re-engineered their famous Google HDR camera with the Pixel 3 and luckily, you can get it on your OnePlus 6 working flawless.
Portrait mode also is way better with the Pixel 3 camera app, especially selfie portraits. You will get a slightly-cropped selfie portrait but with much more clarity, details, and better background exposure control. It’s literally night and day in comparison. Now, to get this Pixel 3 Camera app on your OnePlus 6, you will have to grab the modded Pixel 3 Camera APK file, built specifically for the OnePlus 6.
You will need to be on the latest Android 9.0 Pie. If you have been regularly updating your OnePlus 6, you should already be on Android 9.0. If using custom ROMs, just make sure you are also on Android 9.0 Pie. Does not work for Android 8.0 Oreo.
Download Pixel 3 Camera APK for OnePlus 6 – Link
Credits – XDA