Hello,
Free Eementor version does not have such option as the custom grid builder.
Only WPBakery includes it but you can’t use the WPBakery grid for the Elementor because it another page builder. If you want to change the grid design in your case you need additionally customize theme files. Copy xstore/woocommerce/content-product.php and content-product-slider.php to child theme and edit it according to your needs.
If you don’t have PHP skills you can submit customization request here.
Regards