pp-wp-snippet-add-mime-types.php

<?php
// This code snippet adds additional file types allowed to upload

// Add a custom function to add needed mime types
add_filter( 'upload_mimes', 'add_mime_types' );

function add_mime_types( $mime_types ) {
  
  // add file extensions .svg, .webp, .ai, .eps, .ep, .xml
  // more file extensions can be added just the same
  // for each file type the MIME type is needed
  return array_merge( $mime_types, array(
    'svg'       => 'image/svg+xml',
    'webp'      => 'image/webp',
    'ai|eps|ps' => 'application/postscript',
    'xml'       => 'text/xml'
  ) );
  
}

?>