I suppose you use this helm chart? If so have a look at the Parameter Reference. There are two specific values that set the replica count:

• scheduler.replicas: Airflow 2.0 allows users to run multiple schedulers. This feature is only recommended for MySQL 8+ and PostgreSQL
• workers.replicas: Number of Airflow Celery workers in StatefulSet.

As you want to run jobs in parallel, enabling workers and setting replica to >=2 deploys two workers so jobs can run in parallel.

Updated values.yaml:

airflow:
  workers:
    enabled: true
    replica: 2