“the device-width always corresponds to the width of the device in portrait mode, regardless of whether the device is in that mode or landscape instead. With other devices, its device-width changes depending on its orientation.”
Is this information still valid. And if yes, what versions of iphone does it apply to?
But the best advice it to not even think about individual devices and in fact not use device-width, but use width instead unless there is a special use case for it.
See this post and the associated article:-