Need to add return on a ceiling directly under the furnace and directly over my head during the workday. What can I do to avoid/mitigate this basically being a trumpet pointed at my face when the unit runs?

To clarify, I've worked on cars and motorcycles but I'm otherwise just a random IT guy role-playing as a tradesman to save money. Anyway here are some pictures: https://imgur.com/a/01KKsDg

I have no idea how HVAC documentation works. I expected it to be like automotive and everything else where you can look up model numbers to find diagrams and manuals for service, but apparently it isn't because I searched all these numbers on a sticker I found and got nowhere. There were some documents on the unit itself which you see in the picture of my fat dog.

Rheem Super Quiet 80
Form:
92-102363-11-10
Parts:
92-24161-38-08
92-21519-59-26
92-22166-01-08
92-20802-64-04
92-24399-01-01

I will appreciate any and all advice, but here are my only specific questions really:

1. Where exactly am I supposed to be cutting a hole? I was expecting to see sheet metal duct work, but the existing return air is actually a huge poofy insulated tube. Do I just... Cut it with scissors? HVAC guy I spoke with said I needed to put a takeoff on the unit itself, but I don't really see anywhere that looks built to facilitate cutouts like that.

2. The main reason I'm making this post is because I can look up measures you can take to mitigate sound leakage, but i can't identify which of those will be effective or worth doing in my specific situation without having experience or training (and I have neither). My original plan was to get a boot pointing away from the furnace and run it along the ceiling, but HVAC guy said that would put a lot of strain on the unit for little benefit here. But if it's not worth doing anything like that, aren't I just building a straight pipe from the interior of a running compressor to my own face when I'm at my desk? I want it to be as quiet as possible so I'm willing to do stupid stuff if needed. I'm guessing larger return vent = less noise, right? Can I make the vent like literally 4 ft by 4 ft or something to get it to be silent?