Connecting a pen display to a USB-C port on a GPU

Overview

It might be possible for you to use your USB C port on your GPU. But it also depends on what you're trying to accomplish.

Connecting for power, data, and video

In this case the cable must provide video signal enough power and carry data. Currently I only know of one GPU that has a USB C port that

might work for this case which is the NVIDIA RTX 2080 series. See this article: https://www.eurogamer.net/digitalfoundry-2019-02-28-psa-the-usb-c-port-on-rtx-graphics-cards-isnt-just-for-vr (archive)

To be clear I have never personally tested this scenario with a 2080 card.

Connecting for video only

If a USB C port is on a GPU it should definitely support a video signal.