On an SAT Essay, the CONCLUSION paragraph restates your argument and impresses the grader once last time.

It restates your thesis and 3 examples.

That's it.  The SAT Essay does not call for a true conclusion (i.e. something that you can conclude once your argument has been proven).  A true conclusion should offer more insight into your topic by explaining the relevance or major consequences of your thesis.  The College Board does not give you enough time to do this.  And they don't give their graders enough time to check to see if you did.

It impresses the grader by ending with a relevant hook.

Your final hook could be a controversial statement, a quote, or a specific fact.  It could be a new hook, or just a tie-back to the one from your Intro paragraph.

It's your last chance to boost your score with fancy vocab.