All of the following comes with the caveat that the Kings are incompetent and may do dumb things for dumb reasons at any moment. With that out of the way, there are several problems with this premise.
First, the Kings have a logjam at the guard positions... which you propose to fix by trading them another guard. How does that help them?
Second, you suggest that Smart - a player with little off-ball value who cannot shoot - will somehow be a better fit next to Fox. Why? And why trade for Smart, newly signed to a hefty extension, when they just drafted Davion Mitchell?
Lastly, to get something good, you need to give up something good. Tyrese Haliburton is a solid player still on his rookie contract. Smart isn't getting a conversation started. Given that you've taken the Jays and Rob - the only three players on our roster with any substantial value to a rebuilding team - off the table, I don't think you can expect to acquire Haliburton.
Hield is probably a more realistic target at least, but that still doesn't alter the fact that the Kings don't need Smart.