the S21 doesn't "come" with anything...just the phone. I used a standard issue USB-A to USB-C cable to back up my S21U (via SmartSwitch) to my laptop, no problem.
My laptop only has USB 3.0, the OTG adapter is USB3.0 to USB-C, I would need USB-C to USB3.0 to use the supplied cable and be able to connect to my PC, I'm guessing that will work to be able to transfer my files
If cable stuff doesn't work, you could always use some cloud storage(onedrive, G drive, etc.) to transfer files from your phone to the storage and then grab them from your laptop. There usually a limit to how large the file is of course without paying for any additional storage options.