Baffles will do it If you’re willing to do the work, and based on the fact you’re already ripping holes in walls, I guess you might be
Tear out the wall, baffles against the roof deck in each cavity. At the ridge you’ll need ventilation for the air to escape, ridge venting or otherwise. I’d add 2x3s or 2x4s running horizontally on 16s. You could also just lay them all overtop the existing rafters but if you’ve gone to this point you might as well do it horizontal to avoid the thermal bridging. Laying over top is easier to insulate, up to you. Next insulate, then vapor barrier. I’d use acoustic sealant at the perimeter of your vapor barrier, it’s sticky messy stuff but will help immensely with warm air leakage