I modified the default ScrollBar style starting from the one for version 10.0.17763.0, and created a resource dictionary attached here ScrollBarStyleDictionary.xaml.txt (rename in .xaml).
You can use it as Resource in the Control where you want classic ScrollBars or globally in your Application.Resources.
As example I added the XAML snippet below. In a 2x2 Grid the first row has 2 ScrollViewers and the second has 2 ListView. On both ScrollViewer and ListView in the first column I added the ScrollBarStyleDictionary.xaml and they always show the ScrollBars.
<Grid ColumnSpacing="8" RowSpacing="8">
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ScrollViewer Grid.Row="0" Grid.Column="0" HorizontalScrollBarVisibility="Visible">
<ScrollViewer.Resources>
<ResourceDictionary Source="ScrollBarStyleDictionary.xaml"/>
</ScrollViewer.Resources>
<Rectangle Width="1000" Height="1000">
<Rectangle.Fill>
<LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
<GradientStop Color="Aqua" Offset="0"/>
<GradientStop Color="GreenYellow" Offset="0.5"/>
<GradientStop Color="Red" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
</ScrollViewer>
<ScrollViewer Grid.Row="0" Grid.Column="1" HorizontalScrollBarVisibility="Auto">
<Rectangle Width="1000" Height="1000">
<Rectangle.Fill>
<LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
<GradientStop Color="Aqua" Offset="0"/>
<GradientStop Color="GreenYellow" Offset="0.5"/>
<GradientStop Color="Red" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
</ScrollViewer>
<ListView Grid.Row="1" Grid.Column="0" ItemsSource="{x:Bind _items}">
<ListView.Resources>
<ResourceDictionary Source="ScrollBarStyleDictionary.xaml"/>
</ListView.Resources>
</ListView>
<ListView Grid.Row="1" Grid.Column="1" ItemsSource="{x:Bind _items}"/>
</Grid>
If you want to change the size of a ScrollBars add this "<x:Double x:Key="ScrollBarSize">16</x:Double>" to Application.Resources (global) or specific control Resources.
Let me know, happy to help.