Set Image Sizes

This plugin looks to be just what I need. However I can’t seem to find any equivalent for the add_image_size() function that WP uses for it’s standard featured images.

Is there a way I can display dynamic featured images at specific sizes? If so does it also does it work the the Regenerate Thumbnails plugin too?

Thanks

https://ww.wp.xz.cn/plugins/dynamic-featured-image/