https://doc.arcgis.com/en/experience-builder/latest/configure-widgets/edit-widget.htm
The Edit widget provides users with feature and record editing capabilities in 2D and 3D. Use the Edit widget with another data-connected widget, such as Table, Feature Info, or Map, to allow users to add, delete, and update features in the source data. The geometry mode supports 2D and 3D editing, including move, scale, rotate geometries, and vertices editing. You can choose which fields to display, organize the fields in collapsible groups with meaningful headings, and provide instructions for editing each field. When connected to a map with a form configured for the selected layer, the widget can display the form (including conditional visibility for fields).
The ArcGIS Experience Builder Edit widget may not have the full functionality of the Smart Editor but it should allow for editing vertices of existing features.
Double-check your layer, edit widget (and layer) settings have geometry updates enabled and then try to edit the layer? You may need to double-click an existing feature to expose the vertices
