Everything looked great in the simulator on the iPhone 11 Pro Max. However, I decided to run it on my own device, an iPhone 6s and found that the Plus button in the top right corner was almost entirely off screen.

I thought that this had something to do with the the way that the VStack{HStack{Button()}} was designed but no, that wasn't it.

Solution was to add a wrap the image in a frame using either UIScreen or a GeometryReader. Credit: Stackoverflow

ZStack {
            Image(decorative: "background")
                .resizable()
                .scaledToFill()
                .edgesIgnoringSafeArea(.all)
                .frame(maxWidth: UIScreen.main.bounds.width, maxHeight: UIScreen.main.bounds.height)

This solved the issue.... According to the post:

You have to limit the frame size of the out-of-bounds Image before it is being picked up by the ZStack to avoid the ZStack to grow and so the Overlay to go out of position.