default or selected kernelversion does not have config value CONFIG_EXT4_FS_ENCRYPTION.
Result is shown for kernelversion 6.9.9

CONFIG_EXT4_FS_ENCRYPTION (not configurable)

configname: CONFIG_EXT4_FS_ENCRYPTION

Linux Kernel Configuration
└─>File systems
└─>EXT4_FS_ENCRYPTION
In linux kernel since version 4.1 (release Date: 2015-06-21)