default or selected kernelversion does not have config value CONFIG_F2FS_FS_ENCRYPTION.
Result is shown for kernelversion 6.8.9

F2FS Encryption

configname: CONFIG_F2FS_FS_ENCRYPTION

Linux Kernel Configuration
└─>File systems
└─>F2FS Encryption
In linux kernel since version 4.1 (release Date: 2015-06-21)  
Enable encryption of f2fs 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.