This is not the only way to do this, however from researching and experimentation, I found that the easiest way to do this is to do these steps below.
- Shutdown VM
- Resize Disk in TrueNAS (edit the
zvol
and expand the size to desired) - Add GParted ISO to boot order before HDD
- Boot into GParted live ISO and expand disk size to fill available space
- Remove ISO from boot order
- Boot machine