You are always flying with the core content of …/asobo-aircraft-a320-neo/
except when there is a mod with inside the layout.json file an indication which specific files should be used by the mod’s content when selecting a (what is called in the Aircraft selection) LIVERY.
In case of a simple livery only texture mod, you are still flying the core content with simple modification of the aircraft.cfg, the model.cfg, the texture.cfg, and a bunch of dds-files and thumbnails.
In case of the A32NX there is much more to change (~500+ items) , but you are still flying the core with the advantage of all the changes that makes the a320-neo flyable.
…it is what it is…