Hi Pruthvik,
Greetings from Syncfusion.
We checked your code and the map is rendering as expected. We suspect that you may have missed to add the .json file to the assets folder or you may have missed to add the .json file reference to the pubspec.yaml file. Could you please check these cases?
world_map.json: https://www.syncfusion.com/downloads/support/forum/156198/ze/world_map-1570081224.zip
Reference link: https://help.syncfusion.com/flutter/maps/getting-started#add-a-geojson-file
If you still face any problem, feel free to contact us and we would be happy to help you further.
Regards,
Lakshmi R.