Hello Luke,
USB C to USB C should be possible, but I can't guarantee if you are not using the original cable.
There are other MB16 models that has USB C to USB C directly, so you may consider those.
Also, the power supply could be an issue since supporting to 2 external monitor and UX581 itself could be a heavy loading, or you might need to turn off the screenpad plus, then that's only 3 monitor total.
Thank you.