Method using an older, app supported, version of iTunes.
If you need older apps for that iPad, if you have a computer with an older version of iTunes (version 12.6.5 or earlier ), you can try downloading the most recent versions/s of app/s, by accessing the iOS App Store, through iTunes, logging in using your Apple ID and password, and then, download the most recent version of the app/s you like to use on your iPad, to iTunes on your computer, FIRST.
IF you own a computer with an older version of iTunes already on it, try using that version as an older iPad does not need the latest iTunes version.
If you have a computer, but NO iTunes on it, here is a link to the older 12.6.5 version for download found in this Apple weblink.
iTunes 12.6.5 found here.
Deploy apps in a business environment with iTunes - Apple Support
iTunes 12.6.5 for the Mac requires OS X El Capitàn 10.11.4 or later. Not sure of Windows PC requirements on this version.
You will need to use an older iTunes version and once it is downloaded and installed on your computer, at launch, hold down the Opt/Alt key on your keyboard while launching this older iTunes version, so you can create a new Tunes library.
Then, back on your iPad, you can try to download the latest app from the iOS App Store and if the developer/s has/have left an older, compatible version of their app/s on Apple's app servers, then you will receive a small window pop-up prompt that states that there is an older version of the app that is compatible with your device.. Would you like to download this version now.
Tap the OK button just below the prompt to start the downloading of the older app version to your iPad.
If you are successful in getting apps on this iPad, consider looking for more “up to date”, third party iOS web browsers for that version of iOS.
Since the iPad 4 has not had any new iOS upgrades/updates in over a year, I would strongly consider you stop using that year old, default iOS Safari Web browser and seek out other more current and, up to date and more secure third party Web browsers, instead.
Here are a few, more popular, third party web browsers that I know are STILL being updated and supported on iOS 10 and earlier.
Firefox Web browser
Google Chrome browser
iCab Mobile Web browser
Dolphin Web browser
Dolphin Incognito Web browser
DuckDuckGo private Web browxer
Snow Bunny Web browser
Private Browsing Web browser
Aloha Web browser
Maxthon Web browser
Good Luck to You!