Dynamically setting value for key in coralogix exporter

Question

I am getting journald logs via a fluent bit agent coming through otlp receiver. One of the values provided by logs gather this way is the key service_tag. I want place the value of this key into my coralogix exporter's subsystem key.

How would I do this?

This is my Otel config and I have redacted some information for privacy:

receivers:
  otlp:
    protocols:
      http:
        endpoint: N/A

exporters:
  coralogix:
    domain: N/A
    private_key: N/A
    application_name: "{{  common_env  }}"
    timeout: 30s

service:
  pipelines:
    logs:
      receivers: [ otlp ]
      exporters: [ coralogix ]

I've looked into the different processors but nothing seem work. I really need to a variable like solution but have only seen the use of env vars.