SwiftUI: Scroll only when content does not fit

ViewThatFits.swift

// source: https://fatbobman.com/en/posts/mastering-viewthatfits/

var body: some View {
    VStack(alignment:.leading) {
        Text("Count: \(count)")
        Slider(value: $step, in: 3 ... 20, step: 1)

        ViewThatFits {
            content
            ScrollView(.horizontal,showsIndicators: true) {
                content
            }
        }
    }
    .frame(width: 300)
    .border(.red)
}