Hello @peet1211,

The Woocommerce has already provided the option to manage the image size in category page .

For this you simply need to go Admin Panel > WooCommerce > Settings > Products > Display > Product Images and manage the image size .

Hope this helps.

If you have any confusion further please let us know .

Best Regards!!

Hello @peet1211,

To reduce the width of the product use below given CSS.

For this go to Admin Panel > Appearance > Customize > Additional CSS and paste below given CSS.

.woocommerce ul.products li.product, .woocommerce-page ul.products li.product {
    width: auto;
    clear:none;
}

.woocommerce ul.products li.last, .woocommerce-page ul.products li.last {
     margin: 0 1.8% 15px 0;
}

Hope this helps.

Best Regards!!