Can I get a virus from downloading 3rd party daz assets?
WinAce (an archive manager) had a security breach that permit to execute arbitrary code when opening some archives. Same for libJPEG, the main code used to proceed JPG images. And Daz 3D itself can potentially have the same kind of security breach. So, technically speaking, there's nothing preventing a virus to be spread through none executable files.
But the main issue is DAZ scripting language, that can permit to create a virus. And those files can be automatically proceeded when you open an asset.
Whatever if it's Daz3D assets or something else, as long as you download something from a none official source, there's always a risk. It's at you to decide if the place where you found it is safe (like here by example) or not.