That's an optional USB-PD feature, though (called PPS).

Devices that support it can potentially charge more efficiently (and by extension more quickly, if they're limited by heat dissipation), but they can't rely on any USB-PD adapter supporting it.

It's also different from AVS (which Apple's adapter seems to support), which allows controlling the voltage in finer steps, but not limiting the current in the same way that PPS does.