When creating a post, that's an option under "options".

First described here: #21044

Then added so could also do during the 10 minute Edit window:

SN release: edit-related enhancements #60592

The Brookings report was in an article that was posted elsewhere here on SN (see my other comment with that link). I wouldn't have known about the Brookings report if that SN user hadn't shared that article. There's sometimes value in posting both the source material (e.g., research / report) as well as posting the summary / news article. So I posted the link for the Brookings report, but with sats for upvotes get forwarded (credited) to the other user who shared the article.