Who this is for: The perfect shapes feature requires using iOS 11 or later and only works in the iPad or iPhone app, not on the web.
Draw your shape and hold your finger or stylus on the screen after completing your drawing. Pause for a moment and you’ll see your lines and angles automatically align and straighten. Then you can lift your finger and continue scribbling.
Don’t like the shape correction? Hit undo to revert to your original drawing.