Can I get older (recent) versions of Keynote? I have just updated Keynote to 10.0, and have noticed some loss of features.

In particular, it seems the "typewriter" animation has been replaced with "keyboard".

I recall having the option with typewriter (perhaps other animations too, I forget) to animate text by letter, so that they appeared at random. That is now gone.

Can I either retrieve that feature, or else download the 9. Keynote from before this latest update?

Any questions I have seen similar to this so far are trying to get really old versions. I just want to go back one version.
If you have a Time Machine backup of your drive, then the previous version will be on that.

The Mac App Store will give the date of the latest update: restore a version from earlier than that.