Exlude content for custom post type

Yes. Use the relevanssi_post_content hook to blank out the content for that post type:

add_filter( 'relevanssi_post_content', function( $content, $post ) {
  if ( 'custom_post_type' == $post->post_type ) {
    $content = '';
  }
  return $content;
}, 10, 2 );

Thank you! It looks like this works. Would it also be possible to exclude certain meta fields (made with ACF)?

Yes. You can either list only the fields you want to index in the Relevanssi indexing settings or use relevanssi_index_custom_fields to control things.

Thanks, I got everything working.