JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div class="userCheck">
        <input type="checkbox" id="other" name="Other" value="Other" checked />
        <label for="other">Other</label>
    </div>
    <div class="otherCon">
        <label>If other</label>
        <textarea id="text" name="Other Response"></textarea>
    </div>
    <div>
        <label>More info</label>
        <textarea id="text" name="More info"></textarea>
    </div>

JavaScript

$('#other').on('click', function() {
 if ($(this).is(':checked')) {
  $('.otherCon').slideDown();
 } else {
   $('.otherCon').slideUp();
 }
});