Hi @AnalystOK,
Please provide more details, what type of map? A map can be built with many technologies ArcGIS API for JS, Leaflet, Runtime SDK for Java, Operations Dashboard, ... Depending on the details I would recommend one resource or another.
Assuming you are interested on add data from JavaScript/NodeJS and not Python or anything else (because you are publishing in the ArcGIS REST JS forum, I would recommend you to try the Edit feature data tutorial. But you can also take a look to the Postman collection.
Said that, ArcGIS Feature Services are not the only way to load data into a map, but they are the most versatile 😉.
I hope this helps