If you have a config fragment that you want included in your Linux config file, you can use the make system to add it to the existing config. For example, I have a file called: kernel/configs/ampere-topic-mctp.config that looks like this:

CONFIG_MCTP_TRANSPORT_PCC=m

This tells the make system to change CONFIG_MCTP_TRANSPORT_PCC from the default (=n) to module (=m) when building. To include this config fragment, I append it to the make file command to build the config file. For example:

make olddefconfig  ampere-topic-mctp.config

This can be done with multiple fragments.