Check out example codes for "Make a VStack fill the width of the screen in SwiftUI". It will help you in understanding the concepts better.

Code Example 1

struct ContentView : View {
        var body: some View {
            VStack(alignment: .leading) {
                Text("Hello World")
                    .font(.title)
                Text("Another")
                    .font(.body)
                Spacer()
            }
            .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .topLeading)
            .background(Color.red)
        }
    }

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