This Feature Layer in AGOL (https://www.arcgis.com/home/item.html?id=d26bebb7944d4f7a825a453eca5261b5) has nice popups. However, when I import this layer into my JSAPI app using
const fishLayer = new FeatureLayer({portalItem: {id: 'd26bebb7944d4f7a825a453eca5261b5'}, popupEnabled: true})
To add some more detail to this, if I add a popupTemplate to the above FeatureLayer definition, then it will display when a point is clicked on the ArcGIS JS API custom webapp, but there doesn't appear to be a way to use the popups defined in AGOL.