block-template-examples.php

<?php

/**
 * Register custom block template
 *
 * @return void
 */
function prefix_register_block_templates() {
	
	// Theme pattern example:
	$page_template = array(
		array(
			'core/pattern',
			array(
				'slug' => 'themeslug/some-example-pattern',
			),
		),
	);
	
	// Synced pattern example:
	$page_template =  array(
		 array(
			'core/block',
			array(
				'ref' => 6
			),
		),
	);
	
	// Add it to the existing post type:
	$post_type_object           = get_post_type_object( 'page' );
	$post_type_object->template = $page_template;
}
add_action( 'init', 'prefix_register_block_templates' );