@AvidDabbler - seems to work fine in the current version of the map viewer:
It is not working anymore. I'm trying to integrate Koop with weather APIs. It works on ArcGIS Pro and other JavaScript apps, but it does not work in the web map.

On agol webmap it tried to convert to web-mercartor, but something went wrong....

geoserviceParams: {
f: 'pbf',
cacheHint: 'true',
maxRecordCountFactor: '4',
resultOffset: '0',
resultRecordCount: '2000',
where: '1=1',
orderByFields: 'OBJECTID',
outFields: 'OBJECTID',
outSR: '102100',
spatialRel: 'esriSpatialRelIntersects'
}
if trying with add button

Originally posted by @hildermesmedeiros in #379