Zoom InkCanvas
<ScrollViewer x:Name="scrollViewer" ZoomMode="Enabled" MinZoomFactor="1" VerticalScrollMode="Enabled" VerticalScrollBarVisibility="Auto" HorizontalScrollMode="Enabled" HorizontalScrollBarVisibility="Auto">
<Grid x:Name="outputGrid" Background="{ThemeResource SystemControlBackgroundChromeWhiteBrush}" Height="Auto">
<InkCanvas x:Name="inkCanvas"/>
</Grid>
</ScrollViewer>
Arin Faraj