After publishing to ArcGIS Online, a file geodatabase (FGDB) was created with the RGPF UTM Zone 6S Coordinate System. When opening the feature layer in ArcGIS Pro, transforming it to WGS 1984 Web Mercator (auxiliary sphere) displays the features in the original location.
Share the feature class as a web map or web layer.
Create the feature class on the database with a different coordinate system for the area, such as WGS 1984 UTM Zone 6S. By hosting the feature layer after publishing the file geodatabase, the transformation on ArcGIS Pro to WGS 1984 Web Mercator (auxiliary sphere) works properly.