Installing older versions of Apps on App store.

Greetings,

I recently reseted my iPad Air 2 which is still working immaculately after all these years and passed it down to my son.

However, I have noticed that I can not install Pages, Keynote etc. on the iPad due to their dropped support from iOS 16.

So the question is as follows, how can I install an older version of Pages (ex. V12.1) which is compatible with iPad OS 15.8?

Kind regards.