I had a 9.7" iPad Pro, it has great sound, yes it has 4 speakers, adjusts depending on orientation. It also has a better screen than either your old iPad or the Air 2.
If you hadn't already ordered it I would have recommended going with Apple Certified Refurbished to save a few bucks, it still has new warranty and you can add AppleCare if you want, and it ships fast & free: "We test and certify all Apple refurbished products and include a 1-year warranty. All refurbished iPad models also include a brand new battery, new outer shell and a new white box.":
https://www.apple.com/shop/browse/home/specialdeals/ipad/ipad_pro_97 (what specific configurations they have vary according to availability)
Apple's note on iPad Pro 9.7 speakers:
"
Four Speaker Audio. No matter how you turn it, you’ll want to turn it up.
With a high-fidelity speaker in each corner, iPad Pro creates a rich, wide, and detailed soundstage. It automatically adjusts the orientation of the high frequencies to the topmost speakers, no matter how you’re holding it. So whether you’re playing a game or watching a movie, you — and your ears — will be completely immersed.
"