i think this is what you’re referring to from the FAQ:
Can I use a resolution which isn’t 160x144?
You may use a smaller resolution if your game engine of choice does not produce 160x144. The play area should fit within a gameboy screen. Black bars or ‘super gameboy’ frames around the outside of the gameplay area are fine.
keep in mind, this specific entry is relevant to engines that can’t produce the 160x144 resolution (like Pico-8). if yours does, you should make your game that size. you are free to do whatever decorative borders or other things on your itch.io page though and that does not need to follow the 4-color rule.