default or selected kernelversion does not have config value CONFIG_CRYPTO_BLKCIPHER2.
Result is shown for kernelversion 6.9.9

CONFIG_CRYPTO_BLKCIPHER2 (not configurable)

modulename: crypto_blkcipher.ko

configname: CONFIG_CRYPTO_BLKCIPHER2

Linux Kernel Configuration
└─>Cryptographic API
└─>CRYPTO_BLKCIPHER2
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
source code:
crypto/

depends
CONFIG_CRYPTO