Pass multiple tags slug to rest API

I can pass a single tag slug to WP REST API. But, cannot pass multiple tags slug. It gives an error.

register_rest_route( 'w1/unica/', 'posts/(?P<slug>(a-z0-9)+(?:-(a-z0-9)+)*)', array(
  'methods' => 'GET',
  'callback' => 'unica_get_posts_by_tag',
  'args' => array(
      'slug' => array (
          'required' => true
      ),
      
  )

) );