Hi vizooall,
result image can either be the size of the input image or smaller (there's a checkbox to determine that) but can't be larger.
If you need to just scale up the image you can use any photo editing software to scale it, just make sure you use nearest neighbor filtering so it won't get blurry, and that you increase size in round factors so that pixels will duplicate evenly. But if you do that - ask yourself first if you really need the source image larger and not just scale it in runtime in whatever platform you present the image on?
If you need to scale up the image with actually adding more details to it, and not just duplicate pixels, that's something Pixelator can't do. Adding details to scale up image is a whole different thing and usually involves ML