Hi! No problem. Pixel art is the most easiest thing to increase resolution. In graphical programs you can just scale it flawlessly with the method nearest neighbor. In my game engine - Godot you just need to choose the right import option in settings. I guess Unity also should have something like this. After that you just need to use right scalable object in your editor. I am sorry that I can't help better, I don't know Unity specifics. And English is also no my native language😁