can’t figure out how to make the next / previous block in the modal window

{
$styled = (get_option(‘wp_post_modal_styling’) === ‘1’ ? ‘styled’ : ”);

$close = (get_option(‘wp_post_modal_close’) != ” ? get_option(‘wp_post_modal_close’) : ‘×’);

$HTML = ‘<div class=”modal-wrapper ‘ . $styled . ‘” role=”dialog” aria-modal=”true” aria-label=”‘ . __(‘Popup Dialog’, ‘wp-post-modal’) . ‘”>’;
$HTML .= ‘<div class=”wp-post-modal”>’;
$HTML .= ‘<button type=”button” aria-label=”‘ . __(‘Close’, ‘wp-post-modal’) . ‘” class=”close-modal”> ‘ . $close . ‘ </button>’;
$HTML .= ‘<div id=”modal-content”></div>’;
$HTML .= ‘</div>’;
$HTML .= ‘</div>’;

echo $HTML;

}

how to insert here
?

elseif ( is_singular( ‘post’ ) ) {
// Previous/next post navigation.
the_post_navigation(
array(
‘next_text’ => ‘<span class=”meta-nav” aria-hidden=”true”>’ . __( ‘Next Post’, ‘twentynineteen’ ) . ‘</span> ‘ .
‘<span class=”screen-reader-text”>’ . __( ‘Next post:’, ‘twentynineteen’ ) . ‘</span> <br/>’ .
‘<span class=”post-title”>%title</span>’,
‘prev_text’ => ‘<span class=”meta-nav” aria-hidden=”true”>’ . __( ‘Previous Post’, ‘twentynineteen’ ) . ‘</span> ‘ .
‘<span class=”screen-reader-text”>’ . __( ‘Previous post:’, ‘twentynineteen’ ) . ‘</span> <br/>’ .
‘<span class=”post-title”>%title</span>’,
)
);
}

First you can add the modal-link class like this: https://css-tricks.com/snippets/wordpress/add-class-to-links-generated-by-next_posts_link-and-previous_posts_link/

Then you can modify the link to be only the slug, something like this: https://learncodeweb.com/wordpress/next-and-previous-post-links-customize-in-wordpress/