figure-caption text-center

  <figure class="figure">
    <img src="https://via.placeholder.com/400x300/FFFF00/000000?text=img" class="figure-img img-fluid" alt="図表の画像">
    <figcaption class="figure-caption text-center">図表キャプション中央寄せ（text-center）</figcaption>
  </figure>