I have SanDisk x210 SSD, I read that overprovisioning can increase durability, however I cannot find a way to activate it. Is it possible for SanDisk SSD to use some custom application and set it.
Overprovisioning is an intrinsic property of the SSD. Since it involves hardware, it is not possible to "turn it on".
In some cases, a firmware update can provide a higher level of overprovisioning at the cost of available storage capacity - this involves losing all data on the drive and is supported on a very small selection of drive types, expecially not the x210