How to let 3D model without incorrect shadow and harmony style?

Hi,

I am the beginner of three.js and blender.
I create a model like this

In blender, the model looks like more soft and no black shadow on the top.

When I use three.js to import glb file which is exported from blender, the model is not soft and the black shadow is on the top. I guess causing black shadow is because DirectionalLight.

I really want to set my model style on three.js and the model style likes the both website.

How can I let my model be soft, pure white, no black shadow on the top and the style is similar with google cloud web or dipaul web?

Thanks!