This could be achieved with custom fields or a custom table in the wpdb.
Using ACF (Advanced Custom fields) you could assign a checkbox, or some field to each article and you can allow logged in users to check out certain articles and not allow other users to view that article whilst it is “checked out”… you might have to do some clever code to check when that user closes that article, if they close it without checking the article back in…. If this is something you want to look at doing I could look into this aspect further but if you are after a plugin style solution I will defer to someone else!