default or selected kernelversion does not have config value CONFIG_SYNC.
Result is shown for kernelversion 6.5.1

Synchronization framework

modulename: sync.ko

configname: CONFIG_SYNC

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>Android
└─>Synchronization framework
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option enables the framework for synchronization between multiple
drivers. Sync implementations can take advantage of hardware
synchronization built into devices like GPUs.

source code:
drivers/staging/android/sync.c
selects
CONFIG_ANON_INODES