Package KML layers
Share KML layers
A KML layer cannot be shared as a web layer, but you can share a KML layer in a web map. This simultaneously creates a KML item on ArcGIS Online or Portal for ArcGIS. You cannot share a KML layer within a web scene. You will receive a warning that the layer's data source is not supported, and the web scene will be created without the KML layer.
To learn more about working with KML in ArcGIS Online, see KML.