is 160x144 on the game but can i have let say 500x300 background that not in the game it self?
///MickeI think he is asking if you can put a background around the game that isn't the game, like the graphics that surround Cat Astro Phi.
don't think inkscape is very easy to work with, look at my other comment: https://itch.io/post/56362
In theory you can use Inkscape, but practically you'll most likely have more work getting your stuff to look good later, even if it's just due to reducing the number of colors (Inkscape will use aliasing after all).
Draw a simple character or object, export it as a 16x16 pixel image (Gameboy games typically used 8x8 or 16x16 for tiles and sprites) and see how it looks like and how much work it is for you to get it right (i.e. reduce it to 4 colors or 1 transparent + 3 colors while still looking good)