Is Numbers 12 compatibility with Catalina running on an older MAC?

The last compatible version of Numbers for Catalina is v11.1. If you had previously installed an older version of Numbers from the Mac App Store with the same Apple ID as presently used, you can get Numbers v11.1 for Catalina if you need it.

No. It requires Big Sur 11.0 or later.

Has the Number version 12 been presented which checking in Apple Apps Store under Updates ?

Unless you have used some third-party, so-called cleaner application that might have removed part of the Pages v11.1 application bundle, the application is likely still ok, and the problem may be either cache or preferences related.

I suggest you boot your Mac into Safe Boot mode, see if the height control for cells works there, and then reboot normally. Then try Pages v11.1 again. I don't have Catalina, so cannot test Pages v11.1 as I have Big Sur and Monterey only.

You might also see what the Pages User Guide for Mac has to say about automatic cell height too.