CustomPlayableBehaviour.cs

using UnityEngine;
using UnityEngine.Playables;

// PlayableBehaviourを継承する
public class CustomPlayableBehaviour : PlayableBehaviour
{
    private float _direction = 1f;
    public Transform target;

    public override void ProcessFrame(Playable playable, FrameData info, object playerData)
    {
        if (target != null)
        {
            if (target.position.x >= 1f || target.position.x <= -1f)
            {
                _direction *= -1f;
            }

            target.Translate(Vector3.right * info.deltaTime * _direction);
        }

        base.ProcessFrame(playable, info, playerData);
    }
}

CustomPlayableTest.cs

using UnityEngine;
using UnityEngine.Playables;

public class CustomPlayableTest : MonoBehaviour
{
    private PlayableGraph _graph;

    void Awake()
    {
        // PlayableGraphの作成
        _graph = PlayableGraph.Create("CustomGraph");
        
        // Playableの作成
        var playable = ScriptPlayable<CustomPlayableBehaviour>.Create(_graph);
        
        // PlayableBehaviourの取得
        var behaviour = playable.GetBehaviour();
        
        // PlayableBehaviourのセットアップ
        behaviour.target = transform;
        
        // PlayableOutputの作成
        var output = ScriptPlayableOutput.Create(_graph, "CustomOutput");
        
        // PlayableOutputにPlayableを接続
        output.SetSourcePlayable(playable);
        
        // PlayableGraphを再生
        _graph.Play();
    }

    void OnDestroy()
    {
        // 使い終わったらPlayableGraphを破棄
        _graph.Destroy();
    }
}