Simply use a ScrollViewer

Vertical scrolling page example

<Page
    x:Class="ecu_winiot.PageVentilation"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:ecu_winiot"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <ScrollViewer VerticalScrollMode="Enabled" VerticalScrollBarVisibility="Auto" HorizontalScrollMode="Disabled" >
        
        <Grid Height="1735">  <!-- Height optional, if not present it will auto size based on contents (e.g. the image below) -->
            <Grid.RowDefinitions>
                <RowDefinition Height="1*"/>
                <RowDefinition Height="1*"/>
                <RowDefinition Height="1*"/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="1*"/>
                <ColumnDefinition Width="1*"/>
            </Grid.ColumnDefinitions>

            <!-- BACKGROUND IMAGE -->
            <Image x:Name="imgBackground" Source="Assets/MyImage.png" Stretch="UniformToFill" Grid.ColumnSpan="999" Grid.RowSpan="999"/>

        </Grid>
    </ScrollViewer>

</Page>

FOR MORE SEE SECTION: Scroll Viewer