UWP/WinUI: Override TextBox.HeaderTemplate so that it can display complex content

Question

Is it possible to override TextBox.HeaderTemplate so that it can display complex content - like a StackPanel with multiple items?

<Setter Property="HeaderTemplate">
    <Setter.Value>
        <DataTemplate>
            <ContentControl Content="{Binding}" />
        </DataTemplate>
    </Setter.Value>
</Setter>

I'm trying to do this for testing and it doesn't work.

Answer 1

<ContentControl Content="{Binding Content, RelativeSource={RelativeSource Mode=TemplatedParent}}" />