You can also use the Raspberry Pi 4's USB-C interface, which is normally used to provide a power supply, as a normal USB interface. However, in that case, the Raspberry should supply power via the GPIO pins. You can find clarifications regarding this at https://www.raspberrypi.org/documentation/usage/gpio/. For example, an industrial touch monitor can be connected to the Raspberry Pi 4 via HDMI and USB-C as a touch device. To do this, connect the corresponding cables to the Raspberry and add the following line to the end of the Raspberry configuration file (/boot/config.txt):

dtoverlay=dwc2,dr_mode=host

Instead of being used in host mode, the Raspberry can also be operated via the USB-C port as a peripheral device – e.g., as an Ethernet adapter or as a mass storage device. To do this, add the following line at the end of the Raspberry configuration file (/boot/config.txt):

dtoverlay=dwc2,dr_mode=peripheral

Depending on the intended use, this will require various additional software configuration adjustments. You will find plenty of instructions for this online.