UWP - How to resize SymbolIcon

MainPage.xaml

<Page
    x:Class="UniversalAppTutorials.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UniversalAppTutorials"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <StackPanel 
        x:Name="StackPanel1" 
        Margin="50" 
        Orientation="Vertical"
        Background="AliceBlue"
        Padding="50"
        >
        <!--- Resize symbol icon using ViewBox in XAML -->
        <Viewbox MaxWidth="175" MaxHeight="175">
            <SymbolIcon Symbol="Audio" Foreground="Crimson"/>
        </Viewbox>
        
        <Viewbox MaxWidth="100" MaxHeight="100" Margin="5,5,5,50">
            <SymbolIcon Symbol="AttachCamera" Foreground="HotPink"/>
        </Viewbox>

        <!--- Another way to resize symbol icon in XAML -->
        <SymbolIcon Symbol="Phone" RenderTransformOrigin="0.5,0.5" Foreground="Blue">
            <SymbolIcon.RenderTransform>
                <CompositeTransform ScaleX="5" ScaleY="5"/>
            </SymbolIcon.RenderTransform>
        </SymbolIcon>
    </StackPanel>
</Page>
MainPage.xaml.cs

using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml;


namespace UniversalAppTutorials
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
            // Initialize a new Viewbox instance
            Viewbox viewbox = new Viewbox();

            // Set the Viewbox maximum width and height
            // This will be the width and height of SymbolIcon
            viewbox.MaxWidth = 200;
            viewbox.MaxHeight = 200;
            // Set the margin of Viewbox
            viewbox.Margin = new Thickness(25);

            // Initialize a new SymbolIcon instance
            SymbolIcon symbolIcon = new SymbolIcon(Symbol.Video);

            // Put the SymbolIcon inside Viewbox
            viewbox.Child = symbolIcon;

            // Finally, put the Viewbox on stack panel
            // Programmatically create and resize SymbolIcon
            StackPanel1.Children.Add(viewbox);
        }
    }
}