Pagely doesn’t resize images that are the wrong dimensions (height / width) on the fly.
(Though, if PressThumb is enabled, it will convert them to ‘next gen’ formats and reduce the file size of the image automatically).
For example, if you upload an image to the WordPress admin and then later on register a new image size it won’t try to crop the image on the fly to match the new image size on the front end if you then call that image size in get_the_post_thumbnail() or similar (WordPress VIP, will do this however).
My advice there would be to resize the image (or images) via the WP-CLI wp media regenerate command or similar.
However if you just want to resize a particular image for a particular image and PressThumb is enabled you can do this by modifying the URL.
From Pagely support:
You would want to update the image URL to include the desired dimensions, yes. You can do so by appending -widthxheight after the file name but before the file extension.
As an example, if you wanted to change the dimensions of https://example.com/wp-content/uploads/2021/10/example.jpg to 123 pixels wide by 456 pixels high then the URL you’d need to use for the image would be https://example.com/wp-content/uploads/2021/10/example-123×456.jpg. You can even combine that with optimized webp images by appending .webp to the URL as normal. For something like that, the URL would be https://example.com/wp-content/uploads/2021/10/example-123×456.jpg.webp