I'm not aware of a means to hack device model, but what you're seeing sounds like a bug in the beta.
Is that iphone 11 a registered device in the Member Center?
Was it reported correctly in the release version of Xcode 11?
KMT, Thanks for the reply. The phone is registered to my developer account. I just noticed the "Model iPhone 4" last night, so I had not looked while on earlier XCode nor iOS/macOS. I did file a radar, so we shall see.