The command to add a Venn Diagram or a process chart on PowerPoint Online is to select the Insert tab, then select the SmartArt button, and there is the process charts listed under Process. But the Venn Diagram is listed under List.
In Microsoft PowerPoint, the "Insert" tab includes many features such as "Table", "Images", "Forms" or "SmartArt". "SmartArt" allows users to insert diagram, process, cycle, hierarchy, relation, matrix, and pyramid schemes so that the presentation is more dynamic. Information can be added to those schemes so the audience can easily review it.