How-to increase search results displayed

function posts_per_search_page( $query ) {
  if ( !is_admin() && $query->is_main_query() ) {
    if ( $query->is_search ) $query->set( 'posts_per_page', 10 );
  }
}
add_action( 'pre_get_posts','posts_per_search_page' );

Snippet to functions.php of active theme.

No need to modify the theme or functions.php. Use WordPress ? Custom Post Limits ? WordPress Plugins

That plugin is perfect. It allows me to adjust display results for more than search. Thanks!