A Text Field using HTML syntax is essentially a mini-web page, so you can add links. A potential Use Case is adding links to documents relevant to the model.
The syntax is:
<a href="Your_URL">link text</a>
The model named “HTML Text Fields - Part2” in this folder on my OneDrive has two examples as shown in this screenshot:
Those two text fields contain this text:
The second example — a link to start an email — follows the same basic “<a href>” syntax, but just has a different form for the link, using mailto: instead of https:
I also showed an option in that link to have a Subject added to the draft email. Note that spaces aren’t allowed in the link text, so you need to use the web-friendly code of %20.