When a shape is inserted into a PowerPoint slide, its default appearance is related to the points that it contains. Alter the points, and you can change the original shape to anything you want. PowerPoint’s native Edit Points tool makes it almost a drawing program that provides you the option to play with vertexes (points), handles, etc. This is very similar to what you would do in Adobe Illustrator, CorelDRAW or another drawing program. By using the Edit Points tool, you can change a rectangle to a rhombus, or even edit a curved or freeform line differently.
Alter a shape using the Edit Points option in PowerPoint 2016 for Mac.