This seems like a fairly accurate (yet incomplete) "backport" of `ContentUnavailableView` from iOS 17 to iOS 16.

ContentUnavailableView+Backport.swift

import SwiftUI

@available(iOS 16, *)
struct ContentUnavailableView<Label: View, Description: View>: View {
    private struct VerticalLabelStyle: LabelStyle {
        func makeBody(configuration: Configuration) -> some View {
            VStack(spacing: -1) {
                configuration.icon
                    .font(.system(size: 48))
                    .foregroundColor(.secondary)
                    .padding(.bottom)

                configuration.title
                    .font(.system(.title2, weight: .bold))
            }
                .multilineTextAlignment(.center)
        }
    }

    var label: () -> Label
    var description: () -> Description

    var body: some View {
        VStack(spacing: 3) {
            label()
                .labelStyle(VerticalLabelStyle())

            description()
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
        }
            .padding()
            .padding(.bottom)
            .padding(.bottom, 4)
            .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}

#Preview {
    ContentUnavailableView {
        Label("No Mail", systemImage: "tray.fill")
    } description: {
        Text("New mails you receive will appear here.")
    }
}