Can I Run 32bit Virtual Machine ms on Catalina?

There's a difference between running a 32 bit VM application, and running a 32 bit OS inside a 64bit VM application.

VM applications like VirtualBox, Parallels and VM Fusion have been 64 bit applications for a while now.

Whatever you run inside them, i.e a 32 bit Windows version, is not limited by the Host OS inability to run 32 bit applications.

The VM application takes care of that.

The internal VM image is neither 32 bit nor 64 bit its just a file. The VM application is the one that needs to be 64 bit.

Anything you run inside it, is not affected by the host OS.

Well, according to this article you will be able to run Mojave in a VM that runs under Catalina -- see https://tidbits.com/2019/09/18/moving-to-catalina-keep-your-32-bit-mac-apps-running-with-parallels/ for more info. Have not tried this myself, so am just going by what the article says.

If you try it out let us know how it works.

Good luck...

I would ask Parallels, Fusion, or VirtualBox if their VMs running on Catalina will run a 32 bit OS. I think the way your question is phrased it is causing some confusion. The VM is Parallels, Fusion, or VirtualBox. The OS you run in the VM is the issue. I don't see why an old operating system should not run in the VM if supported by the VM developer. But ask the VM developers.

No. You will need to upgrade to the 64 bit version before upgrading to Catalina.

Are you asking the right question? It appears from your post you want to run 32 bit Parallels, VirtualBox or Fusion. Are you really asking if you can run 32 bit Windows, etc. in your 64 bit VM?