Support to KML

KML format is supported by ArcGIS Enterprise. It can be uploaded to the portal by the Add Item option on My Content and shared.

KML or KMZ files can be added to the map by the options Add Layer from File or Add layer from Web

Some Limitations or the KML format support are:

The following elements do not display in a map: regionated KML, view-based and time-based refresh parameters, regions inside network links, and screen overlays.
Ground overlays and network links without refresh properties do not print.
Image overlays that cover large areas may appear distorted.
By default, there is a 30-minute cache delay in displaying updates to the KML layer. If the layer contains refresh parameters of less than 30 minutes, the shorter interval is honored. If a refresh interval is set on the layer, the refresh interval is honored.
KML layers cannot be used as a basemap.
You cannot set the visibility range for KML layers.
KML layers cannot be reordered in the map contents.
Configuring pop-ups is not supported in KML layers. Any feature data in the layer is automatically displayed in pop-ups; you cannot configure or disable them.
If the portal website is installed on the same network as a KML layer, the KML layer will be accessible in the portal website and Map Viewer; otherwise, internal KML layers are not supported.
KML layers larger than 10 MB cannot be added to maps.