default or selected kernelversion does not have config value CONFIG_EXT4_ENCRYPTION.
Result is shown for kernelversion 6.9.9
Ext4 Encryption
configname: CONFIG_EXT4_ENCRYPTION
Linux Kernel Configuration
└─>File systems
└─>Ext4 Encryption
In linux kernel since version 4.1 (release Date: 2015-06-21)
Enable encryption of ext4 files and directories. This
feature is similar to ecryptfs, but it is more memory
efficient since it avoids caching the encrypted and
decrypted pages in the page cache.
feature is similar to ecryptfs, but it is more memory
efficient since it avoids caching the encrypted and
decrypted pages in the page cache.