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The Metatag module, right out of the box, will come with some default settings that will automatically go to work for you once the module is enabled.

All of these settings can be overridden and implemented from a per-node scope, a per-entity type scope, or a global scope.

The per-node changes are done manually on edit forms. The per-entity and global scopes are handled by going to the Metatag Defaults at Admin menu > Configuration > Search and Metadata > Metatag.

Let's take a look at what we can do here.