Is there any demo to add i3s layer?

CesiumJS
1

Any help thank you

2

CesiumJS does not currently support i3s.

3

You should be able to do what you need with 3D Tiles in Cesium though - check out the getting started guide here (https://cesium.com/docs/tutorials/getting-started/) or the code samples (https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/). Let me know if it helps!