Why is there less ArcGIS Living Atlas of the World content in Portal for ArcGIS compared to ArcGIS Online?

Answer

By design, each ArcGIS Enterprise version contains a fixed subset of the ArcGIS Living Atlas of the World items referencing content in ArcGIS Online. The ArcGIS Living Atlas content life cycles and updates determine the ArcGIS Living Atlas items available in Portal for ArcGIS. However, it is possible to obtain unavailable ArcGIS Living Atlas items out of the box with Portal.

ArcGIS Online users with access to ArcGIS Living Atlas can add the item as a web item to Portal using the item’s REST URL obtained from the item details page in ArcGIS Online.

Refer to Portal for ArcGIS: Add items from the web for steps to add a web item to Portal.

Note:
Store the ArcGIS Online credentials with the added item in Portal.

Additionally, upgrade Portal to access the new and updated ArcGIS Living Atlas content.