Good Morning! 2018 Honda Accord - As I understand it, it is not recommended to use the wireless charger while the phone is plugged into the car and while Car Play is in use. The car has only USB ports as you all know as well.

Has anyone found a USB to USB-C adapter that works with the iPhone 12 power cord?

 

Correct, the phone will not wirelessly charge and cord charge/operate. Doing both may cause overheating.

Any cord will need to be Apple approved if you want it to work properly but you won't have "fast charging". A standard USB to USB-C adapter such as this would be limited in current output:
What people have done is to create a new USB connector that has a separate power source but lets data go to the factory radio. It's basically an adapter with separate power connections. I haven't seen one for the 10th Gen accords yet, but there may be something on eBay.

 

Thanks for your response and info.