It depends on what you're interested in. I have a mod for the creatures of the Unicorn Empire, as I have the campaign of the same name installed. I suggest you go to the forum thread for this campaign, download the NCF_EU_Creatures.pak file, and take a look inside. All files related to the new units are inside.
I was looking for where this folder is, and accidentally gave the wrong model NCF to the Kutrub creature, and before that, I broke the Gnoll. Where is this folder located?