php – WordPress. Filter multiple custom post_type’s in a URL

In my WordPress v5.6, I am using the below code in Author page to show all current author’s posts from a custom post_type, song.

<?php
$author_page_link = esc_url(get_author_posts_url(false, ID->user_nicename));
?>
<a href="' . $author_page_link . '?post_type=song">All Songs</a>

The above link will filter all the songs from current author with a URL below:

http://www.music.com/author/current_author/?post_type=song

I want to show both “song” and “poem” custom posts from a author in the filter page. I have tried below a links, with no luck:

<a href="' . $author_page_link . '?post_type=song+poem">All</a>
<a href="' . $author_page_link . '?post_type=song&post_type=poem">All</a>

How can I have a link to filter posts from multiple custom posts?