Hi Vịt, thanks for checking out the pack! 🙂
Yes, you can switch them to smooth shading on your end. The faceted low-poly look is baked in as custom split normals, so a plain "Shade Smooth" won't change it by itself. Here's what actually works:
Blender: select the mesh, then Object Data Properties (green triangle) > Geometry Data > "Clear Custom Split Normals Data". It goes smooth right away (the faces are already set to smooth underneath).
Unity: select the imported model > Model tab > set Normals = Calculate, Smoothing Angle around 60, then Apply.
Unreal: on import set Normal Import Method = Compute Normals.
Heads-up that they're designed faceted, so smoothing rounds the silhouette and some animals read softer than others, but it works fine. If a few people want it I might add an official smooth-shaded version too. Let me know if you hit any snags!