When you use the Markup tools in Preview, it may seem like there is no way to add something like a shape and then rotate it. You can rotate, however, as long as you use a trackpad. Just select the shape and use two fingers on the trackpad to rotate the selection. Works with text and other elements too. Should work anywhere the Markup tool can be accessed, such as marking up an image in Mail or Photos.
Mac Video Tutorials and Tips for Apple Users
