Does other size of images are Smush it?

HI I would like to know if for example I have an image like: landscape.jpg but if the theme I have created multiple size of that image using: add_image_size so I have like 5 images for example of the original in different sizes. But in the library we can see only one image.

So the question it’s basically when I run Smush Now button or the Bulk Smush all of this generated sizes are optimised as well or only the original image?

Thanks in advance for the information.