Yes, that's the whole point of RAID. What level of RAID you go for depends on the depth of your pockets and the amount of data you want to store.
The simplest is RAID1 which has two drives in a mirrored formation. It's quite possible that your existing PC can do this, depending on the motherboard and space in the case. You should still have some form of external backup as well.
The most common after that for home users is RAID5 which spreads the data across three or more drives at the cost of the capacity of one drive to provide the redundancy. In one job, one drive in a five-drive RAID5 array failed while I was on holiday and no-one noticed any difference in performance.
RAID1 & RAID5 both allow for one drive to fail without losing data. Next is RAID6 where two drives can fail at once without loss of data but with two drives used to give the resilience. For example, five drives in RAID6 will only give three drives of data. After that it gets much more complex and beyond the vast majority of home users. I'll leave investigating RAID50 and 51, etc. as an exercise for the student.
If you need an external box to hold the drives then you can buy a simple two-drive NAS (but buy a decent brand, the sheep response here is Synology but QNAP and Asustor are just as good), pop in a couple of WD Red drives of whatever capacity you want and the job's done. If you want more than two drives then you can buy a four bay NAS (or more) but you're looking at £400 for something worthwhile
plus the drives. If you're prepared to do some work you can either buy an HP Microserver and load the OS of your choice or you can do a full DIY project with your choice of components.
I have or have had all the above options so can give my prejudiced advice on request.....
It might be worth putting a request in the Wanted section to see what pops up....