Zend certified PHP/Magento developer

Page Builder Reduce Images

I am trying to find a way to resize the images in the page builder to a certain width using a field. Is there a way to do this at all? Currently when I select an image from the gallery the desktop image and mobile image have the same final size. As an example I would like to reduce the selected image to a certain width of 500px and place it in the media solder. via phtml this would be no problem but via ko?