Centered Crop Overlay - 2x2 Grid - How To

While cropping, it is common to align a part of the image exactly in the center of the frame, which was difficult to do precisely with a 3x3 grid overlay. However, now you have an option to use a 2x2 grid overlay while cropping an image. This centered crop overlay provides guidance on the center of the image and allows you to precisely crop your image.

I am failing to find how to enable this "2x2 grid overlay". Am I missing a really simple button? Thanks!