Crop tool has no way to affect size of image layers comparable to Canvas size dialog
The Crop tool can be regarded as a more interactive extension of the Image Canvas size dialog.
It lacks a way to resize all layers in an image in a similar way to the Canvas size dialog, though - there's specifically no way to grow layer sizes when growing the canvas size in any direction.
Introducing a similar selection potentially interferes with the Delete cropped pixels and Current layer only settings of the Crop tool.