Add additional file types support in wordpress mainly adobe illustrator files

add-mime-types.php

<?php

function add_custom_upload_mimes( $mimes_types ) {
  $mimes_types['eps'] = 'application/postscript'; // Adobe Illustrator files
  $mimes_types['ai'] = 'application/postscript'; // Adobe Illustrator files
  return $mimes_types;
}
add_filter( 'upload_mimes', 'add_custom_upload_mimes' );