USB-C is just a connector. A cable can be a USB-C connector USB 3.0, power delivery 3.1 cable, or it can be a USB-C connector Thunderbolt 4 cable, or it can be a USB-C connector DisplayPort 1.4 cable.
Yeah, and it also can be a RS-232 compliant serial link cable with 4 wires that are RX, TX, GND, and a +5V for good measure, attached to a USB-C head, can't it? I mean, that'd be totally fine, right?
Yeah and that's the confusing part. Just imagine saying "Yeah this is german power plug, but it might support just 120V, but the device will negotiate once you plug it in.
IIRC you can also run USB 2.0 over a c port
You can have power-only cable (no data transfer) because the PD protocol does not use any usb data wires.