Key Points
options: Define as key: Label pairs. The key is the stored value; the label is what's shown in the dropdown.
default: tutorial → Matches the key tutorial, so "Tutorial" will be pre-selected.
If multiple: true, default can be an array: default: [news, review].
If the default doesn't match any key, the field will fall back to no selection (or placeholder if set).
This works in Statamic 5+ (and earlier versions) for collections, taxonomies, globals, etc.
In the Control Panel
When adding/editing an entry:
New entries: The default option is pre-selected.
Existing entries: Saved value overrides the default.
Frontend Output (Antlers)
This is a standard field configuration option shared across most fieldtypes (see Statamic docs on fields/blueprints). Test it in your blueprint YAML file under resources/blueprints/collections/your_collection/your_blueprint.yaml. Save and refresh the CP!