Build Minecraft storage system automatically (special conditions)?

I have a room on my Skyblock Island with lots of boxes where I store all my things. I have a doublechest for every item. The boxes are always 3 on top of each other with different items. I can't find a YouTube tutorial for this and I'm too poop to invent something myself. Does anyone have a link with a suitable tutorial or can explain it to me?

It's in English but he explained it very well.

Do you know how to build a sorting system so a classic one?

But I always have three boxes on top of each other with different items each. I think he just explained how to stack boxes with the same items on top of each other

Not really, but I can imagine a little

In theory, you just have to put a hopper under the first box, then move the next one a block and so on.

But I have 3 boxes on top of each other with different items, do I have to rebuild the storage with the boxes?

Yes, unfortunately. That's just the space-saving thing or you make it very complicated with an extremely large number of hoppers, which you probably don't want, right?

No, not really. Then I just have to build everything again!

Just make a new island, pre-build everything there and connect a stream of water to the auto sorter and Voila! All you have to do is drop the things in and you're done.

Why a new island? Got a fat pumpkin farm and stuff there. Should I make a storage island or what do you mean?

Yes it goes much faster. Can't explain it simply with text.

OK thanks.