I got the following e-mail from Apple:
To accommodate developers who may need additional time to update their existing apps on the App Store, the deadline for adhering to the requirements below has been extended to June 30, 2020.
- Apps for iPhone or iPad must be built with the iOS 13 SDK or later and use an Xcode storyboard to provide the app’s launch screen.
- iPhone apps must support all iPhone screens and all iPad apps must support all iPad screens.