Many do this mistake with their first iPad.... I did it with my mini 2 8 years ago getting 16GB storage. Corrected the mistake with the mini 4 (64GB) but made the mistake again with the mini 5 thinking 64 would be enough. Times have changes. Nowadays for me even 128GB feels too tight (although clearly more usable than 64). My comfortable starting point has become 256GB.
I guess it all depends what you do with your iPad.
I spent years and years using various iPads with 16GB of storage and only towards the end did that seem pushing my luck, but that was actually because iOS itself had ballooned so there was progressively less and less space for apps and data.
Currently I own a 64GB iPad 9, used mostly for content consumption, and the amount of space I've consumed looks like a mobility scooter in an abandoned aircraft hangar. I could easily have got away with a 32GB version, even though no such version exists.
One's approach for storage needs will generally fall somewhere between these two. You'll want to "go big" if you see yourself taking lots of pictures and videos on it and/or they're high quality (probably more so a thing on iPhones, but work with me here...). Have LOTS of apps. Have lots of files, documents, and multimedia. For video gaming, there are apps that are a mere 50 to 400MB. However, some of them can be in excess of 4 to 9 GB apiece.
For me, I faced the same dilemma when purchasing my 9th gen iPad. 64 or 256 GB? I went with the former. For me, my iPad is pretty much a video gaming device for mobile, tablet, and some iOS only games on the more casual side. Many of my video games are digital board games which are relatively smaller. I don't use it for much anything else. The 2 curveballs ended up being...
1) Apple Arcade
I did the free trial, and yeah, some of the games do cross into the 2 to 8 GB territories.
2) Apple TV (the app and the streaming service)
Also had a free trial of this. I'm able to stream ATV+ from a Firefox browser on a Windows machine, so I didn't need the app. That said, when I was on travel and close to the end of my trial, I ended up bumming off wifi at a cafe, and a supermarket so I could finish up some stuff. I could've also downloaded some shows and movies for offline viewing.
For AA, getting 256 would've put issues of that at ease for sure. For ATV+, I don't really travel, but if I did, 64 GB makes downloading offline videos practically a nonstarter. However, I was annoyed that going from 64 to 256 would've been another $150! I would've liked the option to only pay half that to get only half the storage. It's a bit of a "chicken or egg" situation where I ask myself if I'm not using the iPad much, nor getting back into AA b/c my storage is on the lower side, or is it that I don't use it much, so good thing I choose the lower storage option. Time will tell. :\ I'm still holding off on resubbing to AA since Im more heavily into streaming services these days
