I don’t believe the Graphics Module has any ports on it.
There’s one usb-c port on the Graphics Module see comments below.
Monitor ports will have to be used though the Expansion Cards. The 16" can support 3 display expansion slots on slots 1, 2, and 4. To get a 4th monitor you’d either have to use a usb-c monitor or use a docking station.
Note it’s not recommended to use USB-A expansion slots on ports 1 and 4 due to higher power consumption.
Take a look at the expansion card functionality for the 16"
Indeed, the dGPU module has an USB-C port on the back that carries a DisplayPort signal.
I hardly ever use it, but i did at one point connect an external display to it which worked just fine. I recall that in one of the LTT video’s someone plugged a hdmi expansion card into the back, it looks a bit odd, but it worked just fine.
Yeah propably the best option is to get Thunderbotl4/USB4 certified dock that has the needed ports. There is a thread on the forum of different docks and their “compatibility”.
Not sure if there are reports of using 4 external monitors but I guess it should not be a problem.
Depending on the resolution and framerate of your monitors you could run all 4 off just a single port using an mst hub, the igpu supports 4 displays and the dgpu also support 4. You are however limited to the bandwidth of db1.4 on all the ports.