In AE, make a new comp with the 2048×858 dimensions. Then drag the footage to the comp, and scale it to 106,67%, if it’s 1920×1080. Render to DPX 10 bit or 16 bit, make sure the project bit depth is also at least 16 bit.
I wouldn’t do a XYZ conversion in Resolve (or AE..) Easy DCP and Final DCP both do a good job.
Also interested to hear about the difference between AE and Resolve scaling. I’ve had good experience with Resolve before.