Create In-Line Validation for a Drupal 8 Contact Form

We are a small contract research organization in the pharmaceuticals / biotech field. The Drupal 8 contact form for our business is not working properly. It does not have any validation to make sure all of the fields are filled-in before sending. We want to have user feedback built-in to indicate to the user that each field has been appropriately filled-in. Furthermore, the form should not be sent to us and the user should be informed if the form could not be successfully sent due to missing information. In addition to this project, we are looking for a contractor that could help us with our Drupal 8 site on a regular basis.