Windows – How to you tell if Windows XP is 64bit or 32bit if you only have the partition/filesystem on a hard drive

I'm currently doing my father a favor and setting up an Oracle VM with WinXP on a Win10 host PC. I have the old SSD with his original WinXP partition from some years ago. The data was saved and is accessible on his new Win10 PC. For his convenience I want to set up the same 32- or 64-bit version of WinXP pro as he originally had. But the only way for me to find this out, is to read the old filesystem of the WinXP partition over an IDE-to-USB converter. Since the rest of the computer is discarded, there is no processor whose name I can google. I also tried booting the hard drive with no success.

So my question is: How can I tell if a Windows XP partition is 64bit or 32bit if I only have the filesystem of hard drive mounted as a external USB drive? Like, is there a specific file to read out… or does a specific directory has to exist, or something like that?

^{The old Windows XP Professional filesystem mounted over USB to my (not his) Ubuntu 20.04 machine.}