Hi alexalincatrinoiu,

Even product grid for desktop option helps product items to be even, not resizing images, please see screenshot for better understanding https://prnt.sc/g2V_htGMgP5H

In order to have same size image, I kindly recommend you preparing images you want before uploading them to your media library using the graphic editor (Photoshop or any other) to have a nice-looking grid or You need to find a third party plugin to achieve more functionality that best suits you.

Regards,