NewBehaviourScript.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Playables;

public class NewBehaviourScript : MonoBehaviour
{
    [SerializeField]
    float speed = 1.0f;

    private PlayableDirector playableDirector;

    // Start is called before the first frame update
    void Start()
    {
        this.playableDirector = gameObject.GetComponent<PlayableDirector>();
        this.playableDirector.playableGraph.GetRootPlayable(0).SetSpeed(speed);
    }

    // Update is called once per frame
    void Update()
    {
        this.playableDirector.playableGraph.GetRootPlayable(0).SetSpeed(speed);
    }
}