llmodbls's post in Force all external links into a new tab? was marked as the answer
Usually I just make the link say:
<a href="http://www.whatever.com" target="_blank">link text</a>
So, pretty much just adding target="_blank" inside your link code will make clicking the link open a new tab (or window; depending on the visitor’s browser preferences).
Not sure how to code it to be universal, or if you can. I’ve only ever done it on individual link codes.