Add constrained layout as a block variation.

packages/block-library/src/cover/index.js

@@ -13,6 +13,7 @@ import edit from './edit';
 import metadata from './block.json';
 import save from './save';
 import transforms from './transforms';
+import variations from './variations';
 
 const { name } = metadata;
 
@@ -48,6 +49,7 @@ export const settings = {
 	save,
 	edit,
 	deprecated,
+	variations,
 };
 
 export const init = () => initBlock( { name, metadata, settings } );

packages/block-library/src/cover/variations.js

@@ -0,0 +1,25 @@
+/**
+ * WordPress dependencies
+ */
+import { __ } from '@wordpress/i18n';
+import { cover } from '@wordpress/icons';
+
+const variations = [
+	{
+		name: 'cover',
+		title: __( 'Cover' ),
+		description: __(
+			'Add an image or video with a text overlay — great for headers.'
+		),
+		attributes: { layout: { type: 'constrained' } },
+		isDefault: true,
+		scope: [ 'block', 'inserter', 'transform' ],
+		isActive: ( blockAttributes ) =>
+			! blockAttributes.layout ||
+			! blockAttributes.layout?.type ||
+			blockAttributes.layout?.type === 'constrained',
+		icon: cover,
+	},
+];
+
+export default variations;