Submit A Form With A Button Outside The Form

You can tie a submit button to a form that the button doesn't live inside of. The trick is to give the form an id and then reference that id with the button's form property.

<div>
  <form id="my-form">
    <label for="name">Name:</label>
    <input type="text" name="name"></input>
  </form>

  <!-- ... -->

  <button type="submit" form="my-form">Submit</button>
</div>

With this setup, clicking the Submit button will cause the form to be submitted.

See the MDN Button docs for more details.