By creating a Full URL Targeting Audience you can specifically target certain articles within a webpage, up to 20 subdirectories per domain. For example, nypost.com/2020/08/17/didnt-take-long-for-giants-saquon-barkley-to-impress-joe-judge.  A campaign targeting this Audience will only serve on these exact pages and not the other pages that fall into the category subdirectory.
Enter each URL on an individual line in the ‘Custom Audience’ text box, remove the ‘https://’ and ‘www.’ before the domains if applicabl. This Audience has a limit of 50,000 Full URLs per list.