Hello,
Zoom effect shows the real size of images, if you don’t want the zoom you can disable it in Theme Options > E-commerce > Single Product Page.
If your WC version 3.2.6, this article can be useful for you –
https://docs.woocommerce.com/document/fixing-blurry-product-images/ To change the size of the product images go to WooCommerce > Settings > Product > Display > Image settings + don’t forget to regenerate thumbnails after changes (use Regenerate thumbnails plugin).
Feel free to ask if you have any other questions.
Regards