default or selected kernelversion does not have config value CONFIG_CRYPTO_AEGIS256.
Result is shown for kernelversion 6.9.9

AEGIS-256 AEAD algorithm

modulename: aegis256.ko

configname: CONFIG_CRYPTO_AEGIS256

Linux Kernel Configuration
└─>Cryptographic API
└─>AEGIS-256 AEAD algorithm
In linux kernel since version 4.2 (release Date: 2015-08-30)  
Support for the AEGIS-256 dedicated AEAD algorithm.

source code: