For digital projects which use responsive website technology (e.g. Single Property Websites and Virtual Tours) cropping is not required, so the option does not appear for these project types. Responsive website technology alters the display depending on the size and type of screen the project is being viewed on. This negates the need to crop images for the proper fit.
You can still manually crop images in these types of projects if you like. For instructions on manually cropping images, please see Why does my photo look distorted, pixelated, or lossy?