I'm building a lamp that has (up to) three wall-mounted units connected to a central control box. Each one gets three low-voltage control signal wires and 12V 3A DC power. I'm figuring that a USB PD cable is going to be best for this, just for convenience, but I'm having trouble finding USB PD panel-mount jacks.
If you are making something for your own home office or garage, you can use whatever low-voltage connectors/wires you want, including Type-C connectors.
However, these connectors are designed for high-speed communication with low-profile portable devices in first place, and power delivery is sort-of secondary. As high-speed (10 GHz range) connectors, they typically have 0.5mm pitch and target thin 0.8mm PCBs (half of normal PCB). These parameters are hardly "convenient" to deal with.
More, the Type-c and PD requirements are that initially the connector/port should not have any voltage, and ony if a special signaling over CC wires is detected, the starting voltage is "+5VSAFE", and only after heavy negotiations over PD protocol it is allowed to supply higher voltages.
And I don't want to start about the cost of Type-C cables.
So, for projects like 12-V lamps, it is more convenient to use old-style DIN connectors, like this one, which are better manageable in DIY environment: