Reply To: woocommerce

1) Try this easy code in Additional CSS section:

.woocommerce div.product div.images img {
    width: 50%;
}

2) If 1) doesn’t work refer: https://docs.woocommerce.com/document/image-sizes-theme-developers/

Try: Go to Appearance > Customize > WooCommerce > Product Images set image sizes.

After that you have regenerate thumbnails, without it new thumbnails won’t be updated.