How does one add GB on the iPad?

You will need to consider how you deploy and utilise onboard storage, web storage and also consider incorporating an external SSD device to be honest.

If you’re a heavy user of onboard storage for images , you almost certainly need to instigate a strategy for taking the image and editing on the device - Then saving to external storage be that an SSD or cloud based service .

Similarly for video

For documents these are normally quite small files, however again best on an external SSD.

Consumption music services; most are now online subscription models and to be honest you don’t need the file on the device for the most part.

Music production - you have the wrong device - You need a MacBook Air or better Pro

Drawing and art apps again try and store on an SSD.

Games now many do store quite an amount of data in the other category on the device and these really can eat memory without an easy solutions thats for sure. Other than managing the number of games you actually play - Routinely deleting completed or otherwise unused or unliked games to recapture space

Apps just consider how many you actually have and use. Be ruthless if you haven’t used them for sometime - Delete them period stop

If you need to free up free data storage space on an iPad/iDevice, 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!

( A disclaimer to the immediate advice above. )

If you own an over 7-8 year old to nearly 10-year old iPad, you SHOULD ONLY delete apps that you have ever seldom used or no longer use as there is NO WAY now, in 2020, to retrieve these old apps from the iOS App Store, any longer.

( Third party iOS app developers have permanently removed all of their older, legacy apps from Apple's iOS App Store servers forever!

There are NO more older, common and popular third party apps for old 8 and 9-year old iOS devices, any longer! )

Then, thin out/delete any music/videos/movies/TV shows/podcasts/screen recordings/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 iPads or iPads with a Lightning connector, 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.

iOS devices and iOS/iPadOS need to maintain, at the very least, a minimum of between 2-4 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!

If you actually still have and use a nearly 10-year old iPad 2nd gen, your iPad model is too old, now.

Sorry.

Really time now to seriously consider a new iPad model OR a much “newer” , used iPad model capable of running the latest iPadOS versions. There are plenty of newer, older iPad models that can run the latest, current versions of iPadOS.

Sorry & Best of Luck to You!

You can use external SSD storage

Not with an old, nearly 10-year old, 2011 iPad 2.

That old iPad does NOT support any type of current external storage options.