$sorgu = $db->prepare('SELECT * FROM categories
WHERE id = ?');
$sorgu->execute([
$id
]);

yerine

$sorgu = $db->prepare('SELECT * FROM categories
WHERE id in ?');
$sorgu->execute([
"1,2,3,4,5"
]);

idleri virgul ile ayirarak eklenmeli.
https://www.w3schools.com/sql/sql_ref_in.asp