default or selected kernelversion does not have config value CONFIG_CRYPTO_LIB_BLAKE2S.
Result is shown for kernelversion 6.1.112

BLAKE2s hash function library

modulename: libblake2s.ko

configname: CONFIG_CRYPTO_LIB_BLAKE2S

Linux Kernel Configuration
└─>Cryptographic API
└─>BLAKE2s hash function library
In linux kernel since version 5.1 (release Date: 2019-05-05)  
Enable the Blake2s library interface. This interface may be fulfilled
by either the generic implementation or an arch-specific one, if one
is available and enabled.

source code: