Check this location for device support files:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/
if you don't have folder named iOS 13.6, you need to download device support files.
Download iOS 13.6 device support files from this link: https://github.com/filsv/iPhoneOSDeviceSupport/raw/master/13.6.zip
Close Xcode
Unzip and Paste it in this location: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/
ReOpen Xcode.