I tried this too on macOS 11.6.5 and Xcode 13.2.1. However, Xcode does not show 15.4 as available build option in GUI preferences for current Project. And if I manually change it to 15.4 then build will not happen. So I guess that it is not enough to manually just copy those Support files to /Applications/XCode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport? Or should I connect a real iPhone to Mac when trying to build with 15.4 as it seems that there is no Simulation Support for 15.4 in Xcode 13.2.1?