CODE EXAMPLE FOR HTML

Make Checkbox required

<div class="p-2">
<form action="javascript: void(0)">
  <div>
  <input type="checkbox" name="send_newsletter" id="send_newsletter" required/>
  <label for="send_newsletter">Send me your newsletter</label>
  </div>
    <div>
    <input type="submit" name="submit" value="Submit"/>
    </div>
  </form>
</div>