a.xaml

<StackLayout Spacing="5">
    <Label VerticalOptions="FillAndExpand" 
           Text="{Binding DisplayName}" 
           FontSize="Medium" 
           TextColor="Magenta">
        <Label.Triggers>
            <DataTriggers TargetType="Label"
                          Binding="{Binding IsVIP}"
                          Value="True">
                <Setter Property="TextColor" Value="Blue" />
            </DataTriggers>
        </Label.Triggers>
    </Label>
    <Label VerticalOptions="FillAndExpand" 
           Text="{Binding Email}" 
           FontSize="Small"
           TextColor="Gray" />
</StackLayout>