Does OnePlus 6 also support HDR? I know it's not officially stated but YouTube supports HDR on OnePlus 6. I downloaded a few of the demos and tried playing them in VLC. Upon opening, VLC directed me to "allow modifying system settings" to change screen brightness, I'm assuming it was trying to set it to Max. I enabled it and the video is now playing at full brightness in VLC. However, after trying to play the video again the brightness is not set to Max. I tried reinstalling VLC and playing the video again, this time I didn't get the prompt to enable system modifications as it was off by default for new apps.
YouTube HDR works great everytime, high contrast and brightness set to Max automatically.
I don't know if the display of OnePlus 6 is 10bit but that's highly unlikely.