Hello Andrea, We have added a new Mesh Position node in PixaFlux that allows you to bake 8k position maps. With this node you can bake the maps relative to the model bounding box, the scene bounding box, or a custom bounding box. Here is a video tutorial that shows how to use this new node: https://youtu.be/HPxAdr8acdI…
Quixel's 3DO will bake position maps up to 32k if you need something that large. You don't need a license to Quixel SUITE to use 3DO Baker either, so you can grab it from Quixel.se/suite if you'd like to try the baker out to see if it'll help you! :)