If you're putting a "too big image" in, you're getting a "too big image" out. Nothing magical about that. ;) If you don't want to change it's size, then yes, you'll need to make your level bigger. If your question is about how to shrink the image in Godot, you'll need to check the "Expand icon"-option in the inspector. After that, you'll be able to reduce the button's size below the image-size of the icon. However, you're still loading the original image into memory! So reducing the image-resolution with an external tool (like e.g. GIMP) is the better option for your final game.