Code behind for adding buttons with FontSize binding

MainWindow.xaml.cs

using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;

namespace Wpf.Binding;
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    private AppSession appSession;
    public MainWindow()
    {
        InitializeComponent();
        appSession = new AppSession();
        this.DataContext = appSession;
    }

    private void AddButton_Click(object sender, RoutedEventArgs e)
    {
        var btn = new Button();
        btn.Content = "Added Button";

        ButtonList.Items.Add(btn);
    }

    private void ToggleSizeButton_Click(object sender, RoutedEventArgs e)
    {
        appSession.FontSizeLabel = appSession.FontSizeLabel < 20 ? 32 : 16;
    }
}

public class AppSession : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler? PropertyChanged = (o,e) => {};

    double _fontSizeLabel = 16;

    public double FontSizeLabel { get { return _fontSizeLabel; } set { _fontSizeLabel = value; OnPropertyChanged("FontSizeLabel"); } }

    private void OnPropertyChanged(string name)
    {
        PropertyChanged.Invoke(this, new PropertyChangedEventArgs(name));
    }
}