A monitor arm is almost necessary for a truly ergonomic workstation, especially if it is a stand desk. Since the height between your eyes and the desk can vary and change, especially between sitting and standing, you need a monitor that will rise and lower to the ideal height.
The most capable monitor arm ever created, the Emma can lift up to six displays or 150 lbs of VESA-mounted gear.
Large standing desk converter that can hold 2-3 monitors while providing a good amount of work surface. But be careful of compatibility issues with monitor size, shaky surface while working, and possible wobbly monitors.