I think Tatum can get better, consistent, but I don't see any huge leap.
I know that many fans do not see this as an issue, but Tatum has been playing out of position for the last 2 seasons. He is a wing, not a big. If he could play only as a wing, and not be forced to make up for the lack of a true PF on the team, that alone would allow him to improve.
I am also curious to see how much the monkey that is now off his back will impact him. I think it is clear that he thinks about it (losing in the finals in 2022, losing in the ECF in 2023) and hears all the chatter about it. He is not as good as some players at simply blocking all that out. Now he has nothing to block out. He can just play.