By default all results returned by the World Geocoding Service return the Postal city name for the USA. You can overwrite this by passing in the preferredLabelValues parameter to the REST API and including either 'localCity' or 'matchedCity' as the value.
A Locator View against the ArcGIS World Geocoding Service can also be created and the preferred city to be returned can be changed to either local city or matched city. One the Locator View is create, the organization's administrator can then replace the current World Geocoding Utility service with the locator view option so the whole organization will see results with this option enabled by default.
https://doc.arcgis.com/en/arcgis-online/reference/geocode.htm#ESRI_SECTION1_BC67C473527D4AD4A51F24B5D1A6860C