Oh I understand you better now.
But that's going to be minor. The need for higher wattage is to recharge bigger laptop batteries faster so you need a lot of energy so the powerbank has to be big and the electronics part is small so you'd barely notice it.
You may more able to notice it on the 6700 - 13000 sizes where you'd say say a 6700 15W or a 10000 20W.
For example this teardown
The two USB ports same size, those coils cannot be made smaller and so the only thing you can shrink is those small already black chips. No, I think most obvious change would be just higher upper wattage, noticeably more so in smaller powercore. e.g. the Anker Powercore 20000 PD is currently a 15V maximum which means it would not recharge certain laptops but with GaN you've move that up to say 20V maximum and so do more things.