The Google Play Movies & TV app currently supports 4K HDR technology, so if you have a 4K HDR device or TV, you can take advantage of the great picture quality with the Google app.
This may work with HDR phones such as Sony Xperia XZ Premium, LG G6 and Samsung Galaxy S8. You can also enjoy this technology if you have a Chromecast Ultra and connect it to an HDR-capable TV, so HDR is not yet available. On Android TVs.
Unfortunately, HDR content is still very low, but it is increasing and is expected to increase significantly. You can start looking for HDR content in the Play Store and most movies are said to have a quality version available.