>>7649713 (OP)You do the pixel image in a low-res canvas like 640px or 800x600px in example. And then if you want to re-scale the image maintaining that exact pixel texture you have to change the options in your transform-scale tool, clicking on "nearest-neighbor" so the image will be enlarged keeping the same pixel pattern. Also you can't enlarge the pic just randomly, but in exact proportion, 2x, 4x, 6x etc, or your pixels will be deformed if you enlarge the image in a non binary way. You can't make the picture smaller, it doesn't work like that, you do from small to big with pixel art.
Also you will have to un-toggle any antialiasing rendering options too, etc. You will understand all of these little details along the way.