[tomjen3]

If we can send 4k over a cable it also has the bandwidth to handle 3 screens at HD.

I am not sure that there is a phone that can do that though. I can plug my Android into my USB-C dock and it can display a copy of the screen on the screen, but that is about it. Doesn't even seem to work with the USB keyboard I have plugged in.

[emteycz]

Your phone does not support USB 3.0 then (common with e.g. Xiaomi - these ports are USB-C but USB 2.0). The USB-C on my Samsung can do everything the USB-C on my PC does, including a 4K screen in dual display mode.