RAID 1 with different disk sizes

I am looking at a new HP desktop pc that comes with a 250 gig SSD and a 2TB HDD. I would like to install RAID 1 using the SSD and 250 gig of the HDD, then use the remaining 1.75 gig of the HDD for other storage of relatively static data outside of the RAID array.

Is this possible now with 18.04?

Thanks

Pete