How do I get more GB for my iPad Air 2?

you don't, apart from purchasing a new ipad

you can rent icloud storage but it's not the same as more physical storage on the device read

What's the difference between device storage and iCloud storage? - Apple Support

or you can free up used storage on the device

read

Out of storage error on your iPhone or iPad? Here's the fix! | iMore

and

How to get back 'Other' storage on the iPhone or iPad | AppleInsider

You don't.

What iOS/iPadOS version is this iPad, currently, running?

What is the rated, internal data storage space/capacity of your iPad model and how much of this free, internal data storage capacity is left inside of your iPad model?

I suspect you own a low storege 16 or 32 GBs iPad Air 2.

You should never, ever fill up ANY computer or computing device completely full of data, Ever.

If you need to free up free, internal data storage space on an iOad, you need to start by backing up your iPad to either Apple's iCloud ( you may need to pay for additional, monthly storage space ) or by connecting your iDevice to a computer running the latest iTunes or, if a newer Mac with a much newer macOS, use the macOS Finder to do the device backup and/or some other offsite, “cloud” data storage/backup services, like Google Drive/Photos, BOX, DropBox, Amazon Cloud Drive, Flickr ( for photos/images ), etc.

Then, delete any installed apps that you no longer use or use infrequently enough that they aren't missed (you can always reinstalled any purchased or free apps at some time later, as you need them).

In addition, uninstall any games that appear to be using a sizable chunk of your iPad's internal storage, as well!

Then, thin out/delete any music/videos/movies/TV shows/podcasts/screen recordings/photos-images/eBooks/

eMagazine/iBooks/audio books/Documents/PDFs, etc.

If you use a POP email account on your iPad, delete/thin out any old saved emails that maybe saved to your iPad.

To permanently delete photos/images off of your iDevice go into the Photos app and find the Recently Deleted folder/album and permanently delete any photos/images stored in that folder/album.

Also, you can check to see what other stuff is eating up all your valuable data storage space by going into the Settings App,,General Settings Panel, in the right hand column, tap Storage & iCloud usage panel ( in iOS 11 and later, it’s now called iPad Storage ), in the top Storage Panel, tap the Manage Storage panel, wait for a list of apps to generate that will tell you how much space each app is taking up on your iDevice.

Then, for older iPad models with a Home button, do a hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons.

ALL iOS/iPadOS devices need to maintain, at the very least, a minimum of between 3-6 GBs of free data storage space, AT ALL TIMES, to insure normal/nominal functionalities/operation and general overall performance of any iOS device running iOS/iPadOS.



Good Luck to You!