To have a HTML link open in a new tab, you would write something like:
<a
href="https://letterformarchive.org"
target="_blank"
rel="noopener noreferrer"
>
Letterform Archive
</a>
You can do this in Markdown (depending on which converter you use) without needing to intersperse HTML. Here’s how, using the same link as above:
[Letterform Archive](https://letterformarchive.org){:target="\_blank" rel="noopener noreferrer"}
Automate it
I think a better approach to the above is to set programmatic rules. For example: if I want all external links (i.e. links to other websites) to open in a new tab, I can tell my site generator to do that whilst building the site.
The advantage is that I don’t need to add any special markup and I don’t need to keep track. It just works. I’ve written how to do this here.