Apple's proprietary USB-C to MagSafe 3 connector is required in order to fast charge the new 16-inch MacBook Pro that comes with a 140 W charger. The 16-inch MacBook Pro is the first device to adopt the recently finalized USB-C v2.1 spec that allows for up to 240 W Extended Power Range. Fast charging the MacBook Pro 16 via USB-C should be possible once USB-C to USB-C EPR cables become widely available.
https://www.notebookcheck.net/Apple-16-inch-MacBook-Pro-becomes-the-first-device-to-support-USB-C-Extended-Power-Range-but-140-W-fast-charging-is-limited-to-MagSafe-3-for-now.573806.0.html