How does @State work in ViewModifier or ButtonStyle s...

As far as I know, @State (or @Binding) only works within a View.

If used outside of a view, state changes will not be applied to the View or an error will be encountered stating that it has not been installed on a View.

However, in ViewModifiers or ButtonStyles, @State works well, like in the following example

struct MyViewModifier: ViewModifier {
    @State
    var isHidden: Bool = true

    func body(content: Content) -> some View {
        VStack {
            Button("Toggle Hidden State") { isHidden.toggle() }
            if !isHidden {
                content
            }
        }
    }
}

How dose it works?

I'm guessing it adopts DynamicProperty, Then it makes sense. However, I couldn't find any adaptation codes on the public interface.