JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/findAndReplaceDOMText/0.4.6/findAndReplaceDOMText.js"></script>
<div id="txt">
  <p style="width:100%;">Буквы <i>1123123 буквы</i></p>
  <div style="width:100%;">Буквы 123 буквы
    <div...>
      ...
      <p>Буквы <i style="color:#123456">4211 буквы <img src="" width=200></i></p>
      <p>Буквы <i style="color:#123456">123 буквы <img src="" width=200></i></p>
      ...
  </div>
</div>
</div>

CSS

.myclass {
  color: red;
}

JavaScript

findAndReplaceDOMText(document.getElementById('txt'), {
  find: /\d+/g,
  wrapClass: 'myclass',
  wrap: 'span'
});