With the Android 10 and One UI 2.0 update, Samsung's DeX for PC solution supports the Galaxy S9 and Galaxy Note 9. Around five months ago, it was rumored that the 2018 flagships would receive support for Samsung DeX for PC, a feature that was introduced with the Galaxy Note 10 and Note 10+. That is indeed the case, and those using a Galaxy S9, S9+, or Note 9 can connect their phone to their Windows or Mac PC and use it in a desktop environment with just a USB cable.
DeX for PC is quite the useful tool – it's great for getting work done on documents stored on your phone, playing mobile games with a keyboard and mouse for more accurate control, and dragging and dropping files from your computer to the phone and vice versa. Naturally, the DeX Pad is still the only solution for those who want to use their phone as a PC when they don't have their laptop (or desktop computer) around, while DeX for PC is more for the times when you want to quickly access stuff on your phone or tablet in a convenient desktop interface.
You can download DeX for PC for Mac or Windows from the company's official website. Simply fire up Samsung DeX after it's installed and connect your phone to the PC to start using it. Also, in case you are wondering, you don't need the stable Android 10 update before you can start using DeX for PC – it works with the Android 10 beta as well.