The reason you are unable to set social media links to open in new tabs through our header is because there is not a good way for us to indicate that on an icon-only button. We are trying to adhere to the WCAG recommended techniques of not opening links in new tabs or windows:
Typically, when we do have our application open a link in a new tab, we append a launch icon to the end of the link text. The launch icon itself is labelled "opens in new tab," which helps us avoid having the aria-label on the link, which would then trump the link text itself and fail: https://www.w3.org/WAI/WCAG21/Understanding/link-purpose-in-context. However, with icon-only buttons for social media, we label the icon based on the destination (e.g. YouTube, Instagram, etc.) to pass the link purpose guideline and since we cannot really append a second icon warning that the icon button would open in a new tab, we do not make it configurable.
