How do I add dependencies via the Github web/desktop interface (non-git)?

Question

How do I add dependencies (one repository depends on another) via the Github web/desktop interface? Of course there is how, if there is no specific answer to the question, I also accept alternative methods via Git for example.

I mean, I’m looking for something like:

X repository depends on a Y repository, this Y stays in a Y folder in the default directory that contains X and is automatically updated.

I believe this is how repository dependencies work.

OBS: Access them in Graphs-Dependencies on Github