Minecraft has all kinds of commands that players can use. Of course, these commands can only be used if that particular world allows cheats, since there is a lot that can be done through commands.

A Minecraft shield is a simple but useful defensive tool to aid in pixelated combat, used to block direct melee attacks or projectiles in the sandbox game. Minecraft shields are not upgradable, so ...

You can get a command block in your Minecraft Java or Bedrock world using cheats and a special chat command.