No that one thing isn't trading for a 3rd star. Boston simply does not have the assets to trade for a star without parting with a Jayson Tatum or Jaylen Brown. Kings aren't trading De'Aaron Fox without getting a Jay back. Spurs aren't trading Dejounte Murray without getting a Jay back. Same goes for Philly, Portland, and Washington with Ben Simmons, Damian Lillard, and Bradley Beal.
Anyone who gets paid to write or talk about the Celtics and says any of those players or the like could be acquired for something less than a Jay is simply pandering and clickbaiting.