I want to build multidimensional array at Twig
In Drupal 8 use an Attribute object instead of a multidimensional array:

D7 PHP:

$attributes['attributes']['class'] = array();
$attributes['attributes']['class'][] = 'innerTab';


D8 Twig:

{% set attributes = create_attribute() %}
{% set attributes = attributes.addClass('innerTab') %}


You can use the Attribute object in Twig link():

{{ link(title, support_url, attributes) }}