As you know already, the ASP.NET label controls are translated into HTML inline elements <span> when you load an ASP.NET webform page in the browser:
<asp:Label ID="TopicTitle" runat="server" />
To generate them as HTML heading elements as <H1> or <H2> and so on, you should use another ASP.NET control named Literal and embedded them in the heading tag such as <H1> or <H2>:
<h1><asp:Literal ID="TopicTitle" runat="server" /></h1>