Hosted feature layer: how to either add new field OR export to geodb

[USLEOperations]

In ArcGIS Pro 2.9, I added a hosted feature layer which is hosted by an outside company; it is a polyline-type feature class and in the spatial ref system of WGS 1984. Its attribute table does not contain the true length of the line, which I know I can obtain via the Arcade expression LengthGeodetic($feature,'feet'). Ideally, what I would like to do is add a new field to said table, RealDistance, which such a value for each polyline element in the layer (there are several thousand of such).

Since I cannot add a new field to such in ArcGIS Pro (the layer, coming from the outside source, is obviously read-only), I am trying to figure out a work-around. Can I convert said hosted feature layer to a geodatabase, then modify the geodatabase to add the new field to the attribute table? If so, how?

The end goal is to get the attribute of the hosted feature layer with the additional RealDistance field exported to an Excel spreadsheet, which I can then import into a database.

[HeatherSmith]

Hi @USLEOperations 

I would first go to the item page for the feature layer in ArcGIS Online and check the terms of use section - to confirm that there are no restrictions about making local copies of the data.

If not, then you can use the Copy Features geoprocessing tool to make a local copy of the layer as a feature class in a geodatabase. Once it's a feature class, you can edit it as you like, including adding new fields.