instal the new version for iphoneOld Snook

So, Failing that OR IF NO joy, then there is nothing more to be done. This does NOT mean that every app in the iOS App Store still has an older version of an app that is still compatible with iOS 12 to be able to download/install, per my previous comments on this. These newer iOS/iPadOS devices must use your same Apple ID user account and password. Then go back to your older iPad, open the iOS App Store, go to the Purchases section of the store app, search for the app/s you wish to try and download to that older iPad and see if an older version of the app is allowed to be downloaded/installed to that older iPad. If you own another much newer iOS device that can run iOS/iPadOS 13 and later, you can install the most recent version app/s onto that more recent iOS device. There is one last thing you can try/attempt, if you need to recover older versions of apps, for old or older, aging iOS devices. The immediately above statement is what you really need to worry about. Look for many more third party apps dropping support for all iOS 12 supported devices as the 2022 year progresses. So, it has been over two years, already, and third party app support is already on a downward trend for all iOS 12 supported devices. The last major update to iOS 12 was in 2019, with iOS 12.3. Third party app support, typically, continues for 2-3 years AFTER Apple ends full support of a subset of their devices.

These iPad models are 7-1/2 and 8-1/2-years old, now, in 2022.

These iPad models have overall internal hardware that is too old, too underpowered and incapable of running all of the new, advanced and internal hardware resource intensive features of iPadOS. It is highly possible that your iPad year and model will not ever be able to upgrade/update beyond any version of iOS 12, currently at iOS 12.5.5.

Instal the new version for iphoneOld Snook