The modeling tools (introduced in Spline Beta) enable you to edit geometries to create more complex shapes.
To edit a geometry, press
Smooth & Edit from the Shape panel in the right sidebar. After this, the object will be now converted into a subdivision surface.
You can Extrude, Inset, or generate Edge Loops:
Also, you can modify and dissolve vertices (points), faces (polygons), or edges (lines):
Finally, you can fill holes by selecting the edges:
Under selection settings, you can specify which side should be affected (both or front only). The radius of paint selection can be also adjusted.