This feature is only available for the Portal extension, not the Shared View.
To show the Portal Header Title as HTML, follow these steps:
Go to your Portal's extension settings page.
Under Header & Profile, make sure Show Portal Header is turned on.
Select Airtable Field in Portal Header Title
Select the Airtable formula field containing your HTML code as the Portal Header Title Field
Turn on Show Portal Header As HTML
For a list of supported HTML tags, please have a look at this article.
