Instructions for setting up Ubuntu 20.04 image with XFS file system

Hi there
I’m still unclear from your reply how I could use XFS for the entire file system and then reinstall.

What I want to be able to do is:
Write the Ubuntu OS on to my SD card using Raspberry Pi Imager ideally or another mechanism is fine
Set up the XFS file system on part of that SD card - how can I do this without wiping out the OS, while running this on a single SD card?