get_query_var() where to find docs on this function

Not a lot of details in Codex on that so in a template. such as archive.php use this code to see all the values when you visit an archive page on your blog;

<?php
echo "<pre>"; print_r($wp_query->query_vars); echo "</pre>";
?>

Also see something like:
https://xref.yoast.com/2.7.1/nav.html?_functions/get_query_var.html