Pick any news story and a journalist (from an outlet like NYT, Politico, etc).

Watch the timeline of that journalist's original opinions (and their level of aggression/assertiveness) and then watch how that cascades to either more extremism—if the evolution of the story agrees with their chosen narrative—or, to absolute abandonment of/ignorance of the thing they so fervently held an opinion about a few hours earlier.

Once you start observing this behavior, you will see it happen for nearly all stories. It's like watching rats press a lever to release food pellets and then scattering off to a corner to digest.

I don't know of any good article on the subject, but I think the red/blue war in America is where you can see some of the most extreme examples of this. A simple illustrative example that comes to mind: A politician on the other side of the aisle makes a gaffe, a journalist amplifies the video/text of their statement, based on their followers' reaction a journalist decides if it's something their followers care about and either writes a piece about it with supporting information about just how wrong they are and takes on it from their followers/colleagues or just ignores it and moves on trying to find more red meat for the political partisans that read them.

Amazing displays of the New York Times A-B testing its copaganda headlines in this thread here:

https://twitter.com/nyt_diff/status/1513873661547143176

That account is dedicated to documenting changes to NYT headlines in real-time.