There is currently no ability to create a new feature service within ArcGIS Online. A user needs to have ArcMap or ArcGIS Pro.
Please move the ability to create features that is currently found on the developers.arcgis.com site:
![0EME0000000HMKY](/legacyfs/online/202334_0EME0000000HMKY)
Over to the My Content section of ArcGIS Online.