https://wccftech.com/galaxy-note-9-does-not-require-dex-for-multi-monitor-support/

To use peripherals or an external monitor with the Galaxy S8, Galaxy S8 Plus, Galaxy Note 8, Galaxy S9 and the Galaxy S9 Plus requires the use of a DeX Station or a DeX Pad, but chances are that you will not need that expensive accessory when the Galaxy Note 9 is officially announced on August 9. Apart from getting an upgraded S-Pen, looks like there is something else to look forward to from the imminent launch.

By eliminating the need for docking the Galaxy Note 9, customers will be able to save up money which they can invest in purchasing the upcoming flagship, which is already expected to sport a ludicrous price tag. The Type-C port on the upcoming Galaxy Note 9 is going to be utilizing the DisplayPort interface, meaning that you will easily be able to hook up the device to an external monitor if you want to extend the phone’s screen real estate.