A 2012 iPad 4th generation is 9-1/2-years old and has been fully unsupported and obsolete since 2018.
Upgrading/updating that iPad any farther will never, ever be possible.
If your iPad model has been stuck on iOS 9 or 10 for all of these past years, then it is possible you own an over 9-1/2 to 10-1/2-year old, 2011 iPad 2 or 2012 iPad 3, 4 or 1st gen iPad Mini.
These iPad models cannot ever upgrade beyond iOS 9.3.5/9.3.6 or 10.3.3/10.3.4.
An over 9-1/2 to 10-1/2-year old iPad is far too old and useless, now.
Sorry.
Apple ended support for all 9-11-year old iOS devices nearly 5 years, ago, in 2016.
Third party app developers abandoned and stopped supporting these 8-10-year old iOS devices nearly 3 years, ago, in 2018.
There are, virtually, NO MORE third party apps available from the iOS App Store, any longer!
Third party compatible apps for such old devices are few and far between, now, in 2022.
This includes apps for both iOS 9 AND iOS 10 devices and, throughout 2022, ALL iOS 12 ONLY devices!
AND, NO WAY to, initially, install any older, compatible, third party apps into this old iPad, any longer!
NO MORE SUPPORT! NO MORE APPS!
All 2011-2012 iPad 2, 3, 4 and 1st gen iPad Mini models are fully and completely unsupported AND obsolete!
Sorry, but this is the reality for ALL 9-11-year old AND OLDER iOS devices now. Especially now, in 2022.
In addition, the internal, rechargeable batteries in these old iPads are, also, running on borrowed time.
Not worth the costs to replace these old internal, rechargeable batteries in these old iPads, any longer, either.
I am sorry that you had to learn all of this, but this does not change any of the facts regarding these very old iOS devices.
Please recycle these old devices properly and responsibly.
Sorry & Best of Luck to You!