Thinking of changing the root file system to btrfs

Would this be a case of booting into a live usb
And using btrfs-convert ?

To convert the root file system


Yes, that’s what it does - and you should boot a live USB image to do this - I wouldn’t do this online.

It should all just work - after rebooting the converted rootfs should be recognized as btrfs and just work.

Thanks Ahkok, last question if I wanted to add options to the mounting such as compression how would I do this without using fstab?
Sent with Shift

Your options are /etc/fstab - make it and put in the options, or read how to do this using man systemd.mount mount units.