Most of the feeds I subscribe to came to me in one of two ways:

1. I enjoyed reading an article posted somewhere else (Lemmy, etc.) so I sought out the feed of that publisher.
2. Sometimes news outlets enter into agreements to republish each others articles. When they do this, the re-publisher will usually include a little blurb at the end giving credit to the original publisher. If a feed I’m already subscribed to has an article re-published from elsewhere then I click through and check out the original source to see if I want to follow them as well.