JSFiddle - React, Tailwind, and code Playground

HTML

<form>
<div class="row">
  <textarea id="field" name="field" disabled></textarea>
</div>
<div class="row">
  <label for="checkbox">Разблокировать текстовое поле</label>
  <input type="checkbox" id="checkbox">
</div>
</form>

JavaScript

var checkbox = document.getElementById("checkbox");
checkbox.addEventListener("change",function(){
	var text_field = document.getElementById("field");
  if(this.checked) {
  	text_field.disabled = false;
  } else {
  	text_field.disabled = true;
  } 
});