How to disable folding sidebar

You can now hide the sidebar button, but how to prevent the sidebar from closing (like the settings app, or the Music app...)

import Foundation

import SwiftUI


struct ContentView:: View {
    @State private var columnVisibility = NavigationSplitViewVisibility.detailOnly
    var body: some View {
        NavigationSplitView(columnVisibility: $columnVisibility) {
            List {
               Text("dd")
            }
            .toolbar(removing: .sidebarToggle)
        } detail: {
            VStack{
                Button("Expand"){
                    columnVisibility = .all
                }
            }
            .toolbar{
                ToolbarItem{
                    Button(action:{
                    }){
                        Image(systemName: "square.and.arrow.up")
                    }
                }
            }
        }
    }
}

.constant(.all) was also not possible

import Foundation

import SwiftUI


struct ContentView: View {
    var body: some View {
       NavigationSplitView(columnVisibility: .constant(.all)) {
            List {
               Text("dd")
            }
            .toolbar(removing: .sidebarToggle)
        } detail: {
            VStack{
                 Text("dd")
            }
            .toolbar{
                ToolbarItem{
                    Button(action:{
                    }){
                        Image(systemName: "square.and.arrow.up")
                    }
                }
            }
        }
    }
}