Okay, I found now the hint in documentation:
The values of REQUIRES and PRIV_REQUIRES should not depend on any configuration choices (CONFIG_xxx macros). This is because requirements are expanded before configuration is loaded. Other component variables (like include paths or source files) can ...

I added now some output in CmakeLists.txt


set(priv_requires "componentA" "componentB")

if(CONFIG_DEMO_OPTION1)
list(APPEND priv_requires "componentC")
elseif(CONFIG_DEMO_OPTION2)
list(APPEND priv_requires "componentD")
endif()

message(STATUS "Option 1 : ${CONFIG_DEMO_OPTION1}")
message ...

This was just typo, because I adopted my code. Did try everything like fullclean etc. In sdkconfig.h options are set correct. They are also correct in code like if I do like #ifdef CONFIG_OPTION_1 etc. But like said, in the CmakeLists.txt it get not applied. Do I have to set somewhere to include the ...

I am just trying to following this guide https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/build-system.html#adding-conditional-configuration

But my settings are always ignored and building always results in else() case with "componentE"

my CmakeLists.txt of my compoonent to ...