How to get (number of records with condition) from linking model?

Question

Laravel

There are the following tables: and models Article, Tagand Comment.
When you click on a tag, you need to get a list of articles with a specific tag .

The fact is that the table articlesdoes not know about tags and data can only be obtained from a table article_tagthat does not have a model.
Temporarily solved the issue without models like this:

$countArticles = DB::select( 'SELECT COUNT(*) AS c FROM article_tag WHERE tag_id = ?;', [$tagID] )[0]->c;

But I want it more kosher. I'm waiting for advice.