John Galt wrote:
Apple's Pages / Numbers / Keynote "come with" a new Mac only if you "purchase" them (for $0) when you were offered the opportunity. If you did not take that opportunity at the time, obtaining an older version may not be possible — meaning, I don't know of a way to do that.
Once upon a time, before Apple included Pages, Numbers, and Keynote for free with new Macs, they sold those programs on optical disc as a suite called iWork.
It may be possible to find original copies of iWork for sale on eBay and other places – the catch being that these copies would be so old that they might not be compatible with Catalina (which broke 32-bit programs), let alone Ventura.
In lieu of that possibility, consider purchasing (for $9) LibreOffice, here: LibreOffice on the Mac App Store. It incorporates a presentation app called Impress, and it will work with your iMac.
You can download LibreOffice for free from the developer's site, although they certainly won't mind if you choose to make a donation.