This mod allows any Minecraft player to use a backpack to expand their inventory. The backpack takes up only one slot in the inventory, but inside it there are 27 more cells.
Sophisticated Backpacks Mod for Minecraft 1.16.4
Agree that in this way you can carry several backpacks with you, thereby saving huge space. The backpack can also be installed anywhere as a block and used as a chest.
Download Link: Sophisticated-Backpacks-Mod-1.16.4