If my gig offers one song, for example, and the buyer wants 10. Should I send 10 different offers? He told me to send just one offer. Is There a way I can send just one offer and get the 10 reviews?
1 order 1 review; 10 orders 10 reviews. That’s how it works.
Follow the instructions of your buyer, don’t make things more difficult for them. (They have to pay a fee per-order, and (depending) making them pay more is just… not-right.)
If you want to offer it as a milestone order, so as to be less risky to the both of you, see: https://sellers.fiverr.com/en/article/working-with-milestones