themes-wordpress/poesis/patterns/header.php

<?php
/**
 * Title: Default header
 * Slug: poesis/header
 * Categories: header
 * Block Types: core/template-part/header
 */
?>

<!-- wp:group {"style":{"spacing":{"blockGap":"var:preset|spacing|30"}},"layout":{"type":"default"}} -->
<div class="wp-block-group"><!-- wp:site-title /-->

<!-- wp:site-tagline /-->

<!-- wp:spacer {"height":"30px"} -->
<div style="height:30px" aria-hidden="true" class="wp-block-spacer"></div>
<!-- /wp:spacer -->

<!-- wp:navigation {"layout":{"type":"flex","orientation":"vertical","justifyContent":"stretch","flexWrap":"wrap"},"style":{"spacing":{"blockGap":"var:preset|spacing|20"}}} /--></div>
<!-- /wp:group -->