The boundary between iPhone and iPad thins
Until iOS 26, an app designed for iPhone ran on iPad in a fixed-size window, with the classic black sidebars filling the empty space. iOS 27 and macOS Golden Gate change this: iOS apps are now resizable, allowing users to adapt them to the screen size of the device they are running on — whether an iPad or a Mac via iPhone Mirroring. This is reported by MacRumors and the Platforms State of the Union summary published by Let's Data Science.
Implications for developers and users
For developers, Apple has introduced a resizable iOS Simulator that simplifies testing apps at different sizes without changing the simulation device. For users, the practical benefit is immediate during iPhone Mirroring: apps that previously appeared as small phone-format windows can now occupy more screen on the Mac. This change is particularly relevant in the context of the foldable iPhone — whose form factor will require apps capable of handling variable-size windows — and reinforces the continuity consistency of the Apple ecosystem across devices.