Wish somebody still made the cotton covers without elastic, for garage use - mine are probably 40 years old and getting pretty thin.
They still do the job, though.

BHMA makes an indoor cover but it appears to have elastic? Maybe give them a call and see if you can get one without elastic, I mean they do claim to make "custom" covers. Also the "custom" covers are not refundable so there's a good chance they would make it because of that disclaimer. You pay for it up front and it's YOURS

https://beverlyhillsmotoring.com/collections/car-covers/products/flannelguard-supreme

For the car in your garage. Our FlannelGuard Supreme Car Covers are lined with 100% Cotton and offer the ultimate indoor protection for your special car. Custom-fit from our library of over 100,000 vehicle patters, this stretchable fabric made with a unique combination of Spandex & Lycra will fit your car like an Armani suit.

All Beverly Hills Motoring Car Covers are proudly made in the USA by workers who call America their home. Our indoor car covers are custom fit to your vehicle precisely. We most likely have your car pattern in our database, but if not, give us a call at +1(310) 589-0400 and we’ll measure it. Please note: custom made items are not returnable

The "stretchable fabric" is a non-starter for me; perfect for abrading any dust or whatever into the corners and/or contours of the car.

My old cotton covers merely drape over the cars, and have never left a mark on them.