USB C Connector Wiring and CC pull-downs

Short answer: 5.1k on each of CC1 and CC2 to ground.

The USB C Spec itself, Table 4-25: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf

Good explanations on Stack Overflow here (with a detailed overview of what goes to what) and here.

My favourite USB C socket, for easy routing and soldering, is this one from GCT. A single row of accessible surface mount pins. Make sure you get a longer "stake" length, and/or ensure that the shield pins are properly soldered for strength. Limited to USB2, but that's fine for my projects.