This should help you get it calibrated properly: https://www.rtings.com/tv/reviews/lg/c9-oled/settings
@khaid WebOS is okay but not nearly as good as Roku. You'll probably end up mostly using your Shield.
I don't really see any difference in WebOS or Roku. They are just menu selectors lol. The only advantage to Roku is that it can be updated easily. My TV version of SlingTV and Hulu have been deprecated so I have to launch Roku anyway.
The TCL tv remote is literally a Roku remote. It's so extremely basic that I memorized button placements within a day of using it. That also means the UI super smartly laid out in the roku os so you don't rely on remote buttons to find stuff. I really can't say the same for my shield and apple tv. I fumble around the options a lot.
You should also try out Planet Earth II. It's available via streaming, but I hadn't thought much about it given I have the 4K Blu-ray. The 4K Blu-ray is one of the most impressive 4K/ HDR discs available.