左側にアイテムを置いて、ラベルを画面の中央に配置するには

import SwiftUI

private struct _Book: View {
  
  var body: some View {
    ZStack {
      HStack {
        Rectangle().frame(width: 1)
      }
      
      HStack {
        Text("👾👾👾👾👾👾👾👾👾👾👾👾")
          .anchorPreference(key: MyPreferenceKey.self, value: .bounds) { anchor in
            return anchor
          }
        Spacer()
      }
      .overlayPreferenceValue(MyPreferenceKey.self, alignment: .center) { anchor in
        if let anchor = anchor {
          GeometryReader { proxy in
            HStack {
              Spacer(minLength: proxy[anchor].width)
              
              Text("TitleTitleTitle")
              Spacer()
            }
            .frame(maxWidth: .infinity)
          }
        }
      }
      .frame(maxWidth: .infinity)      
     
    }
  }
}

private enum MyPreferenceKey: PreferenceKey {
  
  static func reduce(value: inout Anchor<CGRect>?, nextValue: () -> Anchor<CGRect>?) {
    value = value ?? nextValue()
  }

  static var defaultValue: Anchor<CGRect>? {
    nil
  }
}

#Preview("Navigation Layout") {
  _Book()
}