How to accurately correspond longitude and latitude with world coordinates?

I want to know the exact world coordinates of a certain latitude and longitude. Is the coordinate of the (0, 0, 0) point after I change the longitude and latitude each time the world coordinate of the current longitude and latitude?

To convert any longitude/latitude/height to Unity world coordinates, first call CesiumWgs84Ellipsoid.LongitudeLatitudeHeightToEarthCenteredEarthFixed to transform the longitude/latitude/height to Earth-Centered, Earth-Fixed Cartesian coordinates. Then, feed those coordinates to the TransformEarthCenteredEarthFixedPositionToUnity method on your CesiumGeoreference object to get the corresponding Unity world coordinates.

If you just want to play an object at a particular longitude/latitude/height, consider adding the CesiumGlobeAnchor component to your game object instead.