I tried with comma:
<ContentPage.Resources>
<ResourceDictionary>
<Style x:Key="large" TargetType="Label">
<Setter Property="FontSize" Value="Large" />
</Style>
<Style x:Key="red" TargetType="Label">
<Setter Property="TextColor" Value="Red" />
</Style>
</ResourceDictionary>
</ContentPage.Resources>
<StackLayout>
<Label Style="{StaticResource large, red}" Text="large red text" />
</StackLayout>
But only the red style was applied.
It seems like later one override the others.
Can I use two or more styles simultaneously?