1. Go to mapshaper.org
  2. Load your region's GeoJSON. In this example, we use the GeoJSON of Uttar Pradesh.
  3. Activate simplify view (top right, Simplify option). You can pick from one of the listed algorithms and a percentage level to simplify the map. Choose a percentage level that doesn't distort the map.
  4. Export the simplified file (top right, Export option)
The exported file will be noticeably different in size.