It's open knowledge to anyone that follows the NBA that James Harden currently wants out of the Houston Rockets. Harden isn't fond of the new regime and the front office and has pushed to try and get traded to a contender. James Harden wants a ring, and he could be the piece that puts a lot of teams over the top and gives them considerably higher odds of winning a championship.
Teams don't have to fulfill a player's request for the destination of their trade. For all we know, James Harden could be traded to the Kings tomorrow. But for a star like Harden, a lot of times teams don't want to commit to the trade unless there's a commitment that Harden will play. That can be used to Harden's leverage to get one of his preferred destinations.
Shams Charania of The Athletic has reported that James Harden has four teams on his list of possible destinations. His original destinations, the Philadelphia 76ers and the Brooklyn Nets are still on the list. Harden has also added the Miami Heat and the Milwaukee Bucks to that list. It seems like Harden doesn't care where he gets traded and is open to a variety of trades, as long as he gets to compete at a high level and possibly make the Finals. Any of these teams would give Harden the chance to play with another superstar, giving him a decent chance to win against anyone.
Harden's priority is obviously to get out of Houston. Sometimes stars don't see eye to eye with management and want to get traded. Harden also wants to compete, and based on his actions doesn't view the Rockets with him as a true contender. As the season gets closer, both parties will hope for a resolution to his trade situation sooner, rather than later.