Yii 2 canonical URL in urlManager configuration

I've got urlManager section in app configuration with several URLs per route:

    'urlManager' => [
        'enablePrettyUrl' => true,
        'showScriptName' => false,
        'enableStrictParsing' => true,
        'rules' => [
            'article-a' => 'article/a', // canonic comes first
            'article-deprecated-a' => 'article/a',
            'article-another-a-is-deprecated' => 'article/a',
            'b-annoucement' => 'announcement/b', // canonic comes first
            'legacy-b-annoncement' => 'announcement/b',
            ...

SEF URLs for routes are stored in frontend/config/main.php as an array, with multiple URLs per route. The first URL for the given route (i.e. /article-a) is canonical and the rest are legacy URLs.

What's the most natural way to specify canonical URL for a group of URLs that are pointing to the same route? It can be either rel="canonical" in view or 301/302 redirect to canonical URL.

Canonical URLs should be preferably specified in a place where the routes were defined (frontend/config/main.php configuration file in this case). The requirement here is that canonical URL should be defined outside of the controller, not hard-coded to controller.