Click the Crop button on the top right under the preview to enter the crop menu and change the input image size.
By default, the aspect ratio is locked to the dimensions of the original image. Click the dropdown to select commonly used aspect ratios.
Click the Lock or Custom to unlock the aspect ratio and manually change the crop rectangle size.
Move the crop handles to change the crop area.
Click Reset to return the original image size. Click the Apply button to save the selection.