It looks like the interior will accommodate a phone with a maximum size of approximately 3 1/2”W x 6 3/4”L. I don’t know the specs of a S20 plus.
This does not wirelessly charge your cell phone. There is a USB port in the back of the device, along with a small pass through hole on the side. This allows you to connect your regular USB charging cable to your phone (charging it) while it is inside the device being sanitized.