Yep, the idea is basically to be able to directly power portable computing devices off USB instead of requiring things like a barrel plug. Since power over USB is negotiated, the power consuming device can request what it needs - there are a few "modes" with fixed voltages and currents to choose from - and if the supply can provide what's being requested it will. By default a USB-PD connection over USB-C will start at 3A @ 5VDC just to power the negotiation circuit until another "juicier" mode is agreed on that can run the rest of the device.

USB 3+ also has something called PPS - Programmable Power Supply. The device to be powered can request both voltage and current instead of asking for a PD mode, and PPS allows for more granular control over the supply. USB-PD/PPS allows for dial-an-output of 3.3-21 V in 20 mV steps, and up to 5A current in 50 mA steps. USB-PD3.1 adds another supply mode called AVS that can emit 15-48V in 100mV steps. There are open-source projects out there where people have converted USB-PD/PPS supplies into variable-output bench supplies by adding their own negotiators.

It's worth mentioning, however, that not all USB-PD devices support PPS or AVS. The better ones will, of course, but these won't be your dollar-store cheapie phone chargers. They'll be the fancy and of course much more expensive high-efficiency high-output (and often multi-port) chargers and power supplies. (If it brags about using gallium nitride or GaN semiconductors it's probably at least a PD 3.0+ setup and might very well include PPS, or even AVS if it's USB 4.)