So i must have 2x Samsung 960 evo with same capacity to create a volume with raid mode ?
Sorry for bad english
Mostly, yes. And same size.
However...what is the purpose of this RAID thing?
RAID 0 - Performance. This really doesn't work with SSD's, especially NVMe drives
RAID 1 - Mirrored. This is not a backup, if that is what you were thinking.