1, With your PrestaShop admin panel, go to Design > Image Settings section.
2, You will see the list of predefined image dimensions. You can enable the image size for the specific type of content directly in the image sizes list.
3, Click on the image size which should be regenerated for editing. You can set your own width and height parameters. Save the changes.
4, Once all the desired image dimensions are changed, click the Regenerate thumbnails button at the bottom of the page.
5, Refresh your website to see the changes. It is possible, you’ll need to clear the PrestaShop cache and browser cache.