https://github.com/apache/airflow/pull/12139 added some new params to the scheduler -- we have "cursory" docs for them in the comments in the config file, but we should have a more details docs in the scheduler.rst page.
airflow/jobs/scheduler_job.py
dag_model.next_dagrun_create_after = None
            else:
                dag_model.next_dagrun, dag_model.next_dagrun_create_after = dag.next_dagrun_info(
                    dag_model.next_dagrun
                )
    def _schedule_dag_run(
        self,
        dag_run: DagRun,
        currently_active_runs: Set[datetime.datetime],
        session: Session,
    ) -> int:
        """
        Make scheduling decisions about an individual dag run
        ``currently_active_runs`` is passed in so that a batch query can be
        used to ask this for all dag runs in the batch, to avoid an n+1 query.
        :param dag_run: The DagRun to schedule
        :param currently_active_runs: Number of currently active runs of this DAG
        :return: Number of tasks scheduled
        """
        dag = dag_run.dag = self.dagbag.get_dag(dag_run.dag_id, session=session)
        if not dag:
            self.log.error("Couldn't find dag %s in DagBag/DB!", dag_run.dag_id)
            return 0
        if (
            dag_run.start_date
            and dag.dagrun_timeout
            and dag_run.start_date < timezone.utcnow() - dag.dagrun_timeout
        ):
            dag_run.state = State.FAILED
            dag_run.end_date = timezone.utcnow()