How to update a DataTemplates (which is a custom view) height and width in xamarin forms? - xamarin

Question

I have a content view which I will be using as a data template for a custom grid view, which will be supporting horizontal scrolling. And for the custom template I need to fix the width and height request depending on the device width and height. Below is the custom content view. How can i update the width and height request values?
<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="GridView.BookshelfItem">
<ContentView.Content>
<Grid BackgroundColor="Black" WidthRequest="320">
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<ProgressBar Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" BackgroundColor="#E4E4E4" Progress="{Binding Progress}" HeightRequest="3" VerticalOptions="EndAndExpand"/>
<Image Source="" Aspect="AspectFill" Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" Grid.RowSpan="3"/>
<Label Text="{Binding Title}" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" Margin="10,0,0,0" VerticalOptions="End" TextColor="#FFFFFF" FontSize="17"/>
<Image Source="icon.png" Aspect="AspectFill" Grid.Row="1" Grid.Column="1"/>
<StackLayout Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2" Margin="10,0,0,0">
<Label Text="{Binding Description}" TextColor="#FFFFFF" FontSize="13"/>
<Label Text="{Binding DescriptionDetails}" TextColor="#FFFFFF" FontSize="15"/>
</StackLayout>
</Grid>
</ContentView.Content>
</ContentView>