I'm aware that the new info.plist file has some new Application Scene Manifest entry as of XCode 11 and iOS 13 only projects, however, what's the benefit of having Enable Multiple Windows option in this manifest, if I only choose that my app is only for iPhone ? giving that the multi-window app experience is only available for iPad apps only.
An app whose target device is only iPhone can still run on iPad. So, Enable Multiple Windows will matter when your app is running on iPad.