The Jabba mod or Just Another Better Barrel Attempt adds mass storage chests that can be upgraded to enormous amounts of items all contained within one block. Each barrel can only hold one type of item but it greatly reduces space requirements for storage.
You can upgrade each barrel up to 7 tiers or rather up to 8192 full stacks of 64 items. That’s an incredible amount of storage for one cubic space. It is costly to upgrade to that point though as you’ll need Structural components as well as storage upgrade parts to get to that emerald level storage.
Of course once you place your chests and fill them to the brim, what happens if you want to move locations? Well this just became a massive undertaking to transport all of this storage to a new locale. Not exactly. This mod adds a dolly making it super easy to transport even the largest of barrels. Plus it can transport any other sort of chest or containment unit from Vanilla minecraft and most mods.