Yes exactly. You plug in the cables and then there's the following conversation:
Laptop: *Om nom nom, 5 volts, yum!*
Power supply: Hey, I can do 5 V, 9 V, 15 V and 20 V
Laptop: I hear ya.
Laptop: Can I get 20 Volts?
Power supply: I hear ya.
Power supply: Here's 20 volts!
You get the idea.
All the way up to whatever the device will accept. Past that, the device rejects the offer from the power supply.
The original spec lists 5 V, 9 V, 15 V and 20 V, with support of for volts being kinda common because that's what cars use so the circuitry support already exists. According to spec, the charger is supposed to support all the voltages lower than it's max, but ofc not everything is spec compliant.
20 Volt @ 5 Amp is 100 watts which was the old maximum power usb-c PD could do. But it turns out that wasn't enough, so they renamed that to be Standard Power Range (SPR) and released when Extended Power Range (EPR). EPR adds adds 28 V, 36 V and 48 V @ 5 Amps, to the spec, for a new maximum of 240 Watts of power.
All the way up to whatever the device will accept. Past that, the device rejects the offer from the power supply.
The original spec lists 5 V, 9 V, 15 V and 20 V, with support of for volts being kinda common because that's what cars use so the circuitry support already exists. According to spec, the charger is supposed to support all the voltages lower than it's max, but ofc not everything is spec compliant.
20 Volt @ 5 Amp is 100 watts which was the old maximum power usb-c PD could do. But it turns out that wasn't enough, so they renamed that to be Standard Power Range (SPR) and released when Extended Power Range (EPR). EPR adds adds 28 V, 36 V and 48 V @ 5 Amps, to the spec, for a new maximum of 240 Watts of power.
(Longer desc of the conversation in table 5 in https://www.ti.com/lit/an/slva842/slva842.pdf )