Hi @pkchari, thank you for your patience!
I’m not sure if there are generic metrics for data size – it certainly depends on the detail and coverage of the data. What types of data are you considering, and for what use cases? (e.g. terrain, buildings, bathymetry)
In the meantime, I can give you numbers for the data that Cesium licenses for offline use.
- Cesium World Terrain is currently 2.5TB.
- Cesium OSM Buildings is 207.7 GB.
- Sentinel-2 imagery (meant to be draped over terrain) is 556.8 GB.