override specific gutenberg block function

gistfile1.txt

if (has_block("gallery", get_the_content())) 
{
  $post_blocks = parse_blocks(get_the_content());
  foreach ($post_blocks as $post_block) 
  {
    if ("core/gallery" == $post_block["blockName"]) 
    {
      $ids = $post_block["attrs"]["ids"];
    }
  }
}
And this is the button:

<button class="gallery" 
<?php
for ($i = 0; $i < count($ids); $i++) {
  $img_link = wp_get_attachment_image_url($ids[$i], "full");
  echo "data-img-" . $i . " = " . $img_link . " ";
}
?>
>
Light Box 
</button>