Is there a way to change the compaction throughput via startup options in Cassandra? We are currently running a Cassandra cluster in K8S containers as Stateful sets. We're considering exposing the config file but we would like to know if perhaps we can provide this value as a startup parameter.
There isn't a command-line option/system property to change the compaction throughput.

You could use nodetool setcompactionthroughput after Cassandra has started.