When working with a hosted feature layer, the editing permissions or capabilities defined by the administrator applies to all users sharing the hosted feature layer. It is not possible to define separate permissions for each member sharing a hosted feature layer within an organization. For example, for one member to only add features, and the other to only update features.
However, as an alternative, a hosted feature layer view can be created to allow the administrator to define different editor settings, styles or filters. The view can be limited to specific features or fields made available to select members for editing. To create a hosted feature layer view, refer to ArcGIS Help: Create hosted feature layer view.