Slow Down Powerup Help

I have been doing days of research trying to figure out how to set up my powerups and have had little luck! I know I have to use Time.timeScale and set that to a number less than one. I am able to get the slow down effect on trigger, but the gameObject does not destroy and the effect is continuous because I am unsure how to set up a timer in my script. Also the I want the player to remain at the normal speed (I've read something about multiplying the slow down speed of the player by a number in order to bring the speed back up to one). I have also read that a normal timer will be affected by the slow down and you must use an alternate timer. I want to do a speed up power up as well. If I can just figure out 1 of these powerups the rest shouldn't be so difficult. Any help or references would be appreciated.

Here's my code:

 using UnityEngine;
 using System.Collections;
 using UnityEngine .Audio ;
 using UnityEngine .SceneManagement ;
 
 void Start(){
 
 }
 
 void update(){
 
 Die();
 
 }
 
 public void OnTriggerEnter2D(Collider2D  other){
 
 if (other.tag == "Slow Down Clock") {
             
             GameObject sound = new GameObject();
             sound.transform.position = transform.position;
             AudioSource audioSource = sound.AddComponent<AudioSource>();
             audioSource.clip = slowDown  ;
             audioSource.Play();
 
             Time.timeScale = 0.5f;
 
             Destroy (sound, slowDown.length);
 
             Destroy (other.gameObject);
 
 
             }
 }
 
 public void Die(){
 
 
         if (ScoreManager.TKOCount > 2) {
 
             GameObject sound = new GameObject();
             sound.transform.position = transform.position;
             int randomClip = Random.Range (0, knockOut  .Length);
             AudioSource audioSource = sound.AddComponent<AudioSource>();
             audioSource.clip = knockOut  [randomClip ];
             audioSource.Play();
 
             Destroy (GameObject.FindGameObjectWithTag ("Player"));
 
             Destroy (sound, knockOut [randomClip ].length );
 
             SceneManager.LoadScene ("GameOver Scene");
 
         } 
             
         if (health.CurrentValue  <=0) {
 
             GameObject sound = new GameObject();
             sound.transform.position = transform.position;
             int randomClip = Random.Range (0, knockOut  .Length);
             AudioSource audioSource = sound.AddComponent<AudioSource>();
             audioSource.clip = knockOut  [randomClip ];
             audioSource.Play();
 
             Destroy (GameObject .FindGameObjectWithTag ("Player"));
 
             Destroy (sound, knockOut [randomClip ].length );
 
             SceneManager.LoadScene ("GameOver Scene");
         }
     }
 
 }