pgs/Assets/Scripts/LightIntensityController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine.Experimental.Rendering.Universal;
using UnityEngine;

public class LightIntensityController : MonoBehaviour
{
    public enum LIUpdatePolicy {
        Update,
        FixedUpdate,
        LateUpdate
    };

    [SerializeField] public LIUpdatePolicy updatePolicy;

    [SerializeField] public bool oscillateIntensity;
    [SerializeField] public float intensityAverage;
    [SerializeField] public float oscillationAmplitude;
    [SerializeField] public float oscillationPeriod;

    [SerializeField] private Light2D light2DController;

    // Start is called before the first frame update
    void Start()
    {
        light2DController = GetComponent<Light2D>();
    }

    void SetIntensity() {
        light2DController.intensity =
            intensityAverage +
            Mathf.Sin(Time.time / oscillationPeriod) * oscillationAmplitude;
    }

    private void Update() {
        if (oscillateIntensity && updatePolicy == LIUpdatePolicy.Update) {
            SetIntensity();
        }
    }

    void FixedUpdate() {
        if (oscillateIntensity && updatePolicy == LIUpdatePolicy.FixedUpdate) {
            SetIntensity();
        }
    }

    private void LateUpdate() {
        if (updatePolicy == LIUpdatePolicy.LateUpdate) {
            SetIntensity();
        }
    }
}