Locked Chests Add-on 1.21+

Mod Locked Chests allows you to lock Chests in Minecraft. Now you can keep your items safe and secure, without fear of them being taken by griefers and other bad people. Moreover, you can easily grant your friends access to the Chests by simply giving them Keys.

There are a total of 8 types of Chests available with different designs.

How does it work?
First, you need to open the Chest.
Interact with the black square in the middle.
Open the inventory again.
And then close it.

How to lock a Chest?
Crouch and interact with the Chest with an empty hand.
Then a menu will appear where you need to lock the Chest.
Two options are available: with the first, you can interact with the Chest at any time, and with the second — only with Keys.
If you give Keys to friends, they can also use the Chest.
Iron, Copper, Gold, and Oxidized Copper are used to craft the Keys.
Keys can also be given names and descriptions.

No one will be able to break a Locked Chest. If someone stole a Key, it can be changed in the Chest settings, meaning you can create a new code. You can have up to 20 Keys.