iiko-features-ext.php

add_filter('wc_iiko_product', function (ProductArg $data, \iiko\classes\Product $iiko_product ){
    if(!empty($iiko_product->tags) && false !== strpos($iiko_product->tags, 'Избранные' )) {
        $data->featured = true;
    }
    return $data;
}, 10, 2 );