Making Smooth Vertex Normals Inside the Shader?

I'm trying to recreate this in order to make my model's normal looks smoother, but i can't get it right sadly. based on what i understand on the demo, he's using both the world position and object position to override the vertex normals inside the shader.

I ended up searching for this because animating my character's face inside blender with custom vertex normals gets ruined every time I animate the face.

Hopefully, someone can help me out.
Thank you very much!