HTML

html modal

<div class="modal" tabindex="-1">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">Modal title</h5>
        <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
      </div>
      <div class="modal-body">
        <p>Modal body text goes here.</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

modal html

<div id="modal-gallery-before-after">
    <div class="popup">
        <div class="popup__overlay" onclick="closeModal()"></div>
        <div class="popup__wrap">
            <div class="popup__close" onclick="closeModal()">
            <svg style="width:16px" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16" fill="none">
                <path d="M15.4905 15.4905C15.3294 15.652 15.1379 15.7802 14.9272 15.8676C14.7165 15.955 14.4905 16 14.2624 16C14.0342 16 13.8083 15.955 13.5976 15.8676C13.3868 15.7802 13.1954 15.652 13.0342 15.4905L7.99963 10.456L2.96504 15.4905C2.63931 15.8163 2.19753 15.9993 1.73688 15.9993C1.27623 15.9993 0.834449 15.8163 0.508721 15.4905C0.182992 15.1648 0 14.723 0 14.2624C0 14.0343 0.0449253 13.8084 0.132212 13.5977C0.219498 13.387 0.347436 13.1955 0.508721 13.0342L5.54331 7.99963L0.508721 2.96504C0.182992 2.63931 0 2.19753 0 1.73688C0 1.27623 0.182992 0.834449 0.508721 0.508721C0.834449 0.182992 1.27623 0 1.73688 0C2.19753 0 2.63931 0.182992 2.96504 0.508721L7.99963 5.54331L13.0342 0.508721C13.1955 0.347436 13.387 0.219498 13.5977 0.132212C13.8084 0.0449253 14.0343 0 14.2624 0C14.4905 0 14.7163 0.0449253 14.9271 0.132212C15.1378 0.219498 15.3293 0.347436 15.4905 0.508721C15.6518 0.670005 15.7798 0.861477 15.8671 1.07221C15.9543 1.28293 15.9993 1.50879 15.9993 1.73688C15.9993 1.96497 15.9543 2.19083 15.8671 2.40156C15.7798 2.61229 15.6518 2.80376 15.4905 2.96504L10.456 7.99963L15.4905 13.0342C16.1525 13.6962 16.1525 14.8111 15.4905 15.4905Z" fill="#CF2144"/>
            </svg>
            </div>
            <div class="popup__item" data-popup ="">
                <div class="appointment__form form--style-full">
                    <div class="modal-gallery-item"></div>
                </div>
            </div>
        </div>
    </div>
</div>
 <div id="<?= get_the_ID() ?>" class="compare__item-<?= get_the_ID() ?>" data-popup="<?= get_the_ID() ?>" onClick="modalGallery(this.id)">
      <div class="modal-image">
           <?php the_post_thumbnail(); ?>
      </div>
      <div class="modal-title">
            <p><?= wp_trim_words(the_content(), 14); ?></p>
      </div>
  </div>