This example using RShiny shows how to add polygons to a map from a geoJSON file to show school catchment areas. The school locations are then plotted.
The geoJSON file used in this project can be found at:
https://spatialdata-accabdn.opendata.arcgis.com/datasets/accabdn::academy-school-catchments-2/about
The coordinates for the schools can be found in the spreadsheet below.