There are apparently two ways to do it automatically: 1) globally: https://stackoverflow.com/questions/56797898/rmarkdown-html-site-yml-navbar-href-links-open-in-new-tab-with-target-blank 2) for each link: https://forum.posit.co/t/how-to-direct-a-link-to-another-tab-in-md-files/48737
There are apparently two ways to do it automatically: