Yes you can. There is a setting called Spacing between the thumbnails which lets you set a distance in pixels, which is applied between every thumbnail. For technical reasons this cannot be % based nor changed with the screen size dynamically. However, it's possible to set a different spacing for mobile devices. Any setting can have a mobile specific value. You can create a custom preset and choose it to be used for mobile devices only.
Different spacing between thumbnails and rows can be achieved via Custom CSS. For example, no spacing between the thumbnails, but 10px spacing between rows.