(I assume you mean "top 23%," since later on you're talking about being in the top quarter. Most of the time "23rd percentile" means "higher than 23% of the group," or top 77%.)
A GPA of 3.81 and a class rank that's barely top quarter suggests that your son's HS awards a whole lot of A's.
If he has standardized test scores that match his grades, a GPA of 3.81 and a rank in the top quartile will make your son a competitive applicant at very many colleges and universities. On the other hand, being in the third decile of the class would probably be a knock against him at many highly selective schools (e.g., Stanford, Princeton, Williams, and also many that aren't quite as selective as those three).
Your son's guidance counselor probably has, or at least has access to, information about colleges and universities where students from his school with similar grades and class rank have been admitted in recent years.
(EDIT: x-post with many above, including Mitch's last post. I almost mentioned Northwestern as a highly selective university where class rank in the 3rd decile could be a problem. On the other hand, if most of the students ranked above him have taken less demanding classes, then that's an issue that your son's counselor can, and should, address in the Secondary School Report.)