default or selected kernelversion does not have config value CONFIG_CROS_EC_TYPEC_ALTMODES.
Result is shown for kernelversion 6.6.78

CONFIG_CROS_EC_TYPEC_ALTMODES (not configurable)

configname: CONFIG_CROS_EC_TYPEC_ALTMODES

Linux Kernel Configuration
└─>Device Drivers
└─>Platform support for Chrome hardware
└─>CROS_EC_TYPEC_ALTMODES
In linux kernel since version 6.6.78 (release Date: 2025-02-17)  
Selectable symbol to enable altmodes.