I think this is definitely a time where we can just trust Jim got the best camera to do the role it needs to play.
Heres a HWR article about it
https://www.hollywoodreporter.com/behind-screen/james-camerons-avatar-sequels-production-sony-venice-cameras-1116600
Cameron and producer Jon Landau's Lightstorm Entertainment confirmed that Sony’s Venice cameras with 3D stereoscopic rigs will be used for Avatar 2 and 3, which will be lensed by Oscar winning cinematographer Russell Carpenter (Cameron's Titanic).
“The Venice camera delivers the most astonishing image I’ve ever seen. The blacks are rich, deep and velvety, the highlights and source lights are amazingly bright. For the first time, we truly appreciate what the term high dynamic range means.”
The camera maker explained that "using the new Sony cabling system, the only part of the Venice carried on the rig will be the image sensor optical blocks, significantly reducing on-board camera weight to about three pounds per sensor block. By lowering the weight and improving ergonomics, Cameron and the Lightstorm team will have the ability to shoot with greater flexibility and freedom." This could include use with Steadicams, drones, gimbals and shooting in confined spaces, a Sony rep added.
Jim seems to really like the HDR and colours... or maybe because it's light to carry. He wouldn't give up picture quality I'm sure of that. Sounds like he's been working with the Sony team aswell to customise it.