Use example of hci_black_box on KW41Z SDK 2.2.1.
Find #define gHciSetTxPowerCommand_c 0x012D
"vendor_debug_commands.h" is no define any function.
Does this TX power command feature allow customers to use it directly without writing a program?
I believe this document is what you are looking for.
Could you please help me check it and confirm if this helps you ?