Right now he's playing at or above a Jaylen Brown level. For that type of player (bonafide all star but not exactly a superstar) to reach the next level, they gotta decide what path they want to take: a scoring pg/big guard (ala SGA, Luka, LaMelo) or a pure scoring mercenary (ala Kobe, KD, Kawhi, etc).
The former involves really ironing out your facilitation skills and understanding of pace. The latter is more about perfecting your kill zone areas and having a "idgaf" mentality. The latter is where i think he should be.
With OKC, him and Chet don't want to step on each other's toes as the 2a/2b guys and don't really want to demand the ball either, even when their role players (Dort) is throwin up bullshyt. They'll have to figure out that syngergy