Marni trunk, medium small or mini?

So I am thinking of getting Marni trunk bag in black for semi formal things that may require a black handbag but unsure about which size I get and the whole soft vs non soft leather thing. I saw people toting Marni medium size and they are bulky! So which size should I get if it’s just for phone, lipstick, wallet, etc? I don’t want to get too small bag that is useless as well. Any thoughts will be appreciated ❤️