nowadays RAID is done with software, on linux if possible. common choices are ZFS and md-raid. you connect drives with SATA or SAS to a computer, and you can add them to a pool. drives added to pool will be formatted once.
hardware raid is discouraged, because if the RAID card fails you need a replacement of the exact same kind, with same firmware version, and they can have other difficulties too that software RAID solutions don't.