PlatformTrigger

using UnityEngine;
using UnityEngine.Events;

public class PlatformTrigger : MonoBehaviour
{
    public UnityEventGameObject OnPlayerStayOnPlatform;
    private void OnTriggerStay2D(Collider2D other)
    {
        Debug.Log("OnTriggerStay2D",other);

        bool isPlayer = other.CompareTag("Player");
        Debug.Log($"isPlayer : {isPlayer}");
        if (isPlayer)
            OnPlayerStayOnPlatform.Invoke(gameObject);
    }
}

[System.Serializable]
public class UnityEventGameObject : UnityEvent<GameObject> { }