Samsung Galaxy S8 supports DisplayPort over its USB Type-C connector allowing it to output video to an external display. We tried to use this phone to output to an Asus PQ321Q using a HDMI cable and the Apple USB-C Digital AV Multiport Adapter.
While the Samsung Galaxy S8 was able to output DisplayPort over its USB Type-C connector and have the Apple USB-C Digital AV Multiport Adapter convert DisplayPort to HDMI, the resulting video on the Asus PQ321Q was extremely small, not too much larger than the screen size of the phone itself. Needless to say, having the video on your display being the same size as the phone's display kind of defeats the purpose of using the larger external display to begin with. Unfortunately there were no ways found on the Samsung Galaxy S8 to control or adjust the size of the external display.