KubernetesPodOperator  pod_template_file content doesn't support jinja airflow template variables. pod_template_file  is part of templated_fields list. 
https://github.com/apache/airflow/blob/master/airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py#L165

template_fields: Iterable[str] = (        'image',        'cmds',        'arguments',        'env_vars',        'labels',        'config_file',        'pod_template_file',    )

But pod_template_file content is not supporting template variables. pod_template_file can be implemented the way SparkKubernetesOperator implemented using template_ext

https://github.com/apache/airflow/blob/master/airflow/providers/cncf/kubernetes/operators/spark_kubernetes.py#L46
 template_ext = ('yaml', 'yml', 'json')
airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py
:type schedulername: str
    :param full_pod_spec: The complete podSpec
    :type full_pod_spec: kubernetes.client.models.V1Pod
    :param init_containers: init container for the launched Pod
    :type init_containers: list[kubernetes.client.models.V1Container]
    :param log_events_on_failure: Log the pod's events if a failure occurs
    :type log_events_on_failure: bool
    :param do_xcom_push: If True, the content of the file
        /airflow/xcom/return.json in the container will also be pushed to an
        XCom when the container completes.
    :type do_xcom_push: bool
    :param pod_template_file: path to pod template file (templated)
    :type pod_template_file: str
    :param priority_class_name: priority class name for the launched Pod
    :type priority_class_name: str
    :param termination_grace_period: Termination grace period if task killed in UI,
        defaults to kubernetes default
    :type termination_grace_period: int
    """
    template_fields: Iterable[str] = (
        'image',
        'cmds',
        'arguments',
        'env_vars',
        'labels',
        'config_file',
        'pod_template_file',
    )
    
    def __init__(