Shield Bash Add-on 1.21+

The shield is no longer limited to just defense and can now help with resource gathering. The mod Shield Bash allows you to break 3x3 blocks in front of you using an ordinary Shield. The ability to break blocks depends on which Pickaxe you use together with the Shield.

The idea is taken from the game Hytale: this feature allows you to break through passages and clear blocks much faster in the game.

All you need is to hold a Pickaxe and a Shield in your hands to quickly break entire walls. Note that you won't be able to quickly mine Diamond Ore if you're holding a Stone Pickaxe.

However, the Shield loses durability when used.