I saw on this page ( https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/arcgisonlinefeatures/ft-parameters-w.htm ):
The ArcGIS Online Feature Service writer performs a truncation by reading all feature IDs from the layer, and then making deletion requests in batches according to the Features Per Request advanced parameter.
I was wondering if there were plans to incorporate the ArcGIS REST API Truncate operation?
https://developers.arcgis.com/rest/services-reference/truncate-feature-layer-.htm