In a completely clean room environment where a designer had never seen a folding phone, but had all the context of the iPhone and everything Apple had done, they would develop almost exactly the same design and features.
Designers have also been exploring the concept of foldable devices for literal decades, well before any reached the market. I have an industrial design and technology degree, we did a project in 2005 where we explored the designs around this, looking at the UI, the physical interaction, everything. My design had a similar aspect ratio and size, as I am sure half the student did my year and every other year they ran the project. (the iPhone Duo is about thousand times better than my design though!)
Thats not to say the Microsoft designers didn't do an incredible job, they did, but they were building on decades of design ideation from those that had experimented before them.