$sortings = new Collection();

$birthYearFilter = Sorting::propertySort("Birth year", "ascending");

# Sort the entries by birth year first, after that by creation timestamp
$sortings->add($birthYearFilter);
$sortings->add(Sorting::timestampSort("created_time", "ascending"));

return Notion::database("8284f3ff77e24d4a939d19459e4d6bdc")
    ->sortBy($sortings)
# ->sortBy($birthYearFilter) // both sortBy variations work!
    ->query()
    ->asCollection()
    ->each(function ($entry) {
        echo $entry->getTitle() . PHP_EOL;
    });