Currently when you configure a service with Scale Based symbology and you view the 'Feature Service' in a Map Viewer in Enterprise the symbology at small scales is not visible. It works great on a 'Map Service' but not on 'Feature Services'. There currently is NO workaround.
Most users want to add a layer from their content to a map and be able to see varying symbology at different scales but cannot do this.
Here is the documentation of for scale based symbology: https://pro.arcgis.com/en/pro-app/latest/help/mapping/layer-properties/scale-based-symbol-classes.ht...
We are unable to view this type of scale based symbology in a Web Viewer in Enterprise for Feature Services.