In Bedrock, you can summon it directly by typing slash summon Warden, while on Java, the command to summon it is Minecraft colon Warden.

Now you can summon an entity using the execute command, which this bug disallowed Fixed particles when using animation controllers to play particles and switching to a different state that also ...

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