1. https://forum.infinity-code.com/viewtopic.php?id=808
I recommend ArcGIS script version.

2. By default, there is no way. But if you have programming experience, you can use OnlineMapsControlBaseDynamicMesh.OnMeshUpdated to modify the vertices and make the mesh a bit sphere-like.
http://infinity-code.com/doxygen/online … cb5e68a1a1

And how to sink all the vertices so that a large mesh looks like part of a sphere(earth).

Thanks very much!