Earlier quoted context omitted.
If 140MW is more than USB PD can deliver, then how can the other side of the cable be USB-C?
Because the 140W charging adapter supports USB-C EPR (extended power range) [0], which allows compatible USB-C chargers, cables, and devices to work at up to 240W. (Obviously Apple's 140W charger only supports up to 140W.) However, the spec is so new that there's currently no USB-C to USB-C cable that supports 140W. I don't think we know yet if the MacBooks can charge at 140W with an EPR USB-C cable, not least becaus…
140W charging on the 16" had me worried that Apple was using a proprietary/non-conforming extension to USB-C, just like Nintendo did for the Switch. The reports of bricked Switches from standard USB-C chargers was an unfortunate demonstration of why this is a bad idea, and why it's important that Apple is using a standard (even if it's very new) method of increasing power delivery.