For the vast majority of people, burn in is not an issue on OLED.
It can only become an issue if you have relatively the same content displayed for hundred/thousands of hours. The static content also needs to be bright and saturated. If is dark, it is less risky. So if you play the same video game with a static bright HUD for months/years or always have bright yellow subtitles on, then it is a risk. But if you simply watch movies/TV shows, no worries.
If you are really worried, just make sure the prevention features are turned on, and that you vary the content you watch.