Check out google map’s panning, how zooming works, how panning only pans to a certain extent, depending how far you are zoomed, with a smooth edge to the pan. Is this possible using CesiumJS?
Welcome to the community! We really appreciate that you are taking the time to bring us your questions 
I am not sure exactly what functionality you are looking for. Could you potentially share a video or a gif that showcases what you want?
The key here is the Camera object. Please read through our documentation - it should help you out with your implementation. In particular, the member defaultRotateAmount may be crucial.
https://cesium.com/learn/cesiumjs/ref-doc/Camera.html?classFilter=camer
Let me know what you think! I am looking forward to learning more.
-Sam