Spent about an hour looking for this answer, all the solutions we found required a JavaScript solution. But it doesn't, just add the red code to your <li> tag
Couldn't believe how simple this was to do.
<li class="tab-btn"
onclick="location.href='template.php?acct_id=<?php echo $_GET['acct_id']; ?>';">Social Media</li>
<a class="btn btn-success" href="
https://www.google.com"
target="_blank">Google[/url]
And use target="_blank" to open the link in a new tab.