Just got a Rift S today only to find it's not working with my system. I got the Cable Matters USB-C to Displayport adapter recommending by a lot of people online, as the USB-C on my model of laptop is for displayport specifically and connected to my 1660TI. The damn thing just won't work though, although the USB connects just fine, I can't get any output from the displayport. I've updated every driver, my BIOS, restarted the computer, updated the firmware on the Rift S, and I'm at a complete loss.
Do you have onboard (Discrete Intel) as well as a dedicated GPU?
If the GPU doesn't have a path to the port it isn't going to work - it may be possible to disable the onboard graphics or to at least make the GPU primary (if Nvidia the control panel may allow you to try this)