I am using flyToBoundingSphere method, but dont know how to set the “endTransform” so that the camera are looking directly down?
How do I do that?

Hi @theuns, have you tried using the offset instead? The offset determines the position and orientation of the camera (relative to the bounding sphere) after the flight is completed.

See the definition of cameraOffset in this Sandcastle. If you change the second argument to Cesium.Math.toRadians(-90.0), the camera will be looking directly down on the object.