Default 'Image' Block - Cropping Ratio

The image Block with the starterkit has the option for cropping ratio. How do I make this effect the cropping on the front end? I have looked at the snippet>blocks>image file but cant see how I would achieve this? Is this possible?

Create a copy of the default image block snippet in site/snippets/blocks with the same name image.php. You can find here the default code here: image | Kirby CMS. Adapt as required.