A sample WordPress block template part

footer-contact-info.html

<!-- wp:group {"layout":{"type":"constrained"}} -->
<div class="wp-block-group"><!-- wp:group {"layout":{"type":"constrained"}} -->
<div class="wp-block-group"><!-- wp:columns -->
<div class="wp-block-columns"><!-- wp:column -->
<div class="wp-block-column"><!-- wp:paragraph {"align":"right"} -->
<p class="has-text-align-right">Our Main Office<br>123 Test Street<br>Test, NY 15000<br>212-555-5555</p>
<!-- /wp:paragraph --></div>
<!-- /wp:column -->

<!-- wp:column -->
<div class="wp-block-column"><!-- wp:paragraph -->
<p><strong>Connect with us:</strong></p>
<!-- /wp:paragraph -->

<!-- wp:social-links {"className":"is-style-logos-only"} -->
<ul class="wp-block-social-links is-style-logos-only"><!-- wp:social-link {"url":"https://www.facebook.com","service":"facebook"} /-->

<!-- wp:social-link {"url":"https://www.twitter.com","service":"twitter"} /-->

<!-- wp:social-link {"url":"https://www.linkedin.com","service":"linkedin"} /--></ul>
<!-- /wp:social-links --></div>
<!-- /wp:column --></div>
<!-- /wp:columns --></div>
<!-- /wp:group --></div>
<!-- /wp:group -->

footer.php

// Add a Block Template Part to the footer.php template.
<?php block_template_part('footer-contact-info'); ?>

functions.php

// Add Block Template Part Support: https://learn.wordpress.org/tutorial/using-block-template-parts-in-classic-themes/
function add_block_template_part_support() {
    add_theme_support( 'block-template-parts' );
}
 
add_action( 'after_setup_theme', 'add_block_template_part_support' );