I personally would go as big as you can find. My Hermann's seems to really enjoy his 4' x 4' indoor enclosure. I doubt you'll find a bookcase that big, but that would be a good goal if you have the space!
I wouldn't be afraid of putting something together yourself, it is much easier than it looks! For some easy options to try to give the tort more space- I have seen some people buy bookshelves that they remove the shelves from and lay on the back. I've also seen some people get decent space out...
An infrared thermometer will be your best friend with tortoise care. I definitely recommend one for measuring more exact temps of your tort and around their enclosure.
Would love to see some pictures! Getting a tort is very exciting but I definitely understand how some of their behaviors (like the leg pumping) can be pretty scary at first glance. He's probably all good and just getting used to his new space. :)
Just as a quick extra tidbit- you can read a little more on this in the FAQ
https://tortoiseforum.org/threads/why-do-my-tortoises-legs-move-when-hes-resting.148876/
Hi Jenny, I suspect your tortoise is ok. They'll pump their front legs back and forth for breathing pretty frequently. You'll probably want to add some more details here for anyone else that sees this thread. You'll inevitably be asked for species and such :p
Can't say I've seen these on desktop or on mobile. Definitely recommend a trusted ad-blocker like uBlock Origin if you are having issues!
https://github.com/gorhill/uBlock#installation
I think if you are near Boise there are a few places you could take him to. I live up in northern Idaho and I haven't seen anything close to me though. :/
I hope you can get this cute little guy the care he needs!