I don't think OKC needs to do that much.
I love their Big Three of SGA, J-Dub, Chet. I also love their role players of Giddey & Dort.
They need a legit backup big man. If they could find a way to get someone like a Varejao to come off the bench behind Chet, that would be ideal. Allow them to big with a twin towers approach at times.
Cason Wallace is an interesting young backup PG. Isaiah Joe a young backup SG.