Most current Android smartphones have a 720p (HD) or 1080p (FHD) display. Smartphones like the Samsung Galaxy 21 come with a 1440p (WQHD +) display. But there are very few such phone models that are expensive at the moment.
But with this you can watch 2160p (4K) videos on YouTube from any Android smartphone.
What is the real significance of this? How can I watch 4K videos without the relevant display?
In fact, your video will play at the same resolution as your display. This means that if your display is 1080p, the video will play at the same 1080p resolution.
But this way when you watch videos from 2160p you will have a better fast internet connection and more data than before.
Some phones that have been updated to version 16.07.32 of the YouTube App have been able to use this feature, but many have not yet implemented it. An upcoming update will allow everyone to experience this feature.