Currently the initialization of Kafka when Kafka pod is starting, and it is done via a series of ENV value. If we want to change a setting that is not taken by an ENV, we need to add it in the script and rebuild the container. Or use CUSTOM_SCRIPT env value. 
 
It can be done via the init container and property files are in a config map. It is easier to change a Kafka setting. We just need to redeploy helm charts.