<Window x:Class="WpfApp1.MainWindow"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
          xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
          xmlns:local="clr-namespace:WpfApp1"
          mc:Ignorable="d"
          Title="MainWindow" Height="450" Width="800">
     <Grid>
          <Grid.ColumnDefinitions>
               <ColumnDefinition />
          </Grid.ColumnDefinitions>
          <Grid.RowDefinitions>
               <RowDefinition Height="Auto" />
               <RowDefinition Height="Auto" />
          </Grid.RowDefinitions>

          <StackPanel Grid.Column="0" Grid.Row="0" >
               <Button Height="220" Margin="10">Add Text1</Button>
          </StackPanel>

          <StackPanel Grid.Column="0" Grid.Row="1" >
               <Button Height="320" Margin="10">Add Text2</Button>
          </StackPanel>
     </Grid>
</Window>

<Window x:Class="WpfApp1.MainWindow"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
          xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
          xmlns:local="clr-namespace:WpfApp1"
          mc:Ignorable="d"
          Title="MainWindow" Height="450" Width="800">

     <ScrollViewer CanContentScroll="True" VerticalScrollBarVisibility="Auto">
          <Grid>
               <Grid.ColumnDefinitions>
                    <ColumnDefinition />
               </Grid.ColumnDefinitions>
               <Grid.RowDefinitions>
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
               </Grid.RowDefinitions>

               <StackPanel Grid.Column="0" Grid.Row="0" >
                    <Button Height="220" Margin="10">Add Text1</Button>
               </StackPanel>

               <StackPanel Grid.Column="0" Grid.Row="1" >
                    <Button Height="320" Margin="10">Add Text2</Button>
               </StackPanel>
          </Grid>
     </ScrollViewer>

</Window>