You'd likely have to make it Bagley, Hield, & our 2020 1st to make it attractive/competitive enough. Beal seems like the only potential guy at the moment considering he would be a good fit next to Fox, is still somewhat young, is locked up for a few more years, and is not happy with his current situation.
Having said that, I feel like any of these deals are going to be difficult to pull off because of Hield. If the Wizards are trading Beal (26), why would they want Hield (27)? For that matter, why would any team want to trade a star for a 27 year old player when (more often than not) a trade like that indicates a rebuild? Hield would have to go to another team with young assets being redirected to WAS, and in the case of trying to send Hield to a 3rd team, why wouldn't that 3rd team cut the Kings out and try to acquire the better & younger Beal for themselves?
They obviously would need the assets to acquire someone like Beal but you'd think that if a team is in the market for a SG, they would likely try to acquire Beal first.
Even if we did acquire Beal for a package like that, we still aren't good enough to becomes a championship contender...
Fox/Joseph
Beal/James
Barnes/Bogdan
Bjelica
Holmes/Dedmon
That's not good enough to be a top team, and we wouldn't really have any cap space in the 2020 offseason to add talent. Your only chance really is to trade Bogdan for a future pick and then let Bjelica, Holmes, Dedmon, & Joseph walk in the 2021 offseason. You'd have ~$30 mil in cap space to add around Fox, Beal, Barnes, James, & 2021 1st. I don't believe $30 mil is enough for a max player so this type of idea seems shortsighted to say the least.