Thanks for the reply.
Yes I know about the size already.
But the issue is that it is nearly impossible for me to add all the images again with larger size.
As this option is must set in a js file I think, we should be able to change the size, right?
Can you tell me which file contains the related code for the size?
Sorry, but this function will not work if you don’t have original images larger than images shown in the product gallery. Zoom function comes with WooCommerce plugin and its JS code is located in /wp-content/plugins/woocommerce/assets/js/frontend/single-product.min.js