How to create buttons with script?

I want to create Buttons for my Level Selector automatically. I use the code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class Levels : MonoBehaviour
 {
     Button locked;
     Button unlocked;
 
     Rect rc;
 
     private GUIStyle guiStyle = new GUIStyle();
 
     public Texture lockedTexture;
     public Texture unlockedTexture;
 
     public int levelAmount;
     int level = 1;
 
 
     void Start()
     {
         
     }
 
     void Update()
     {
               
     }
 
     void OnGUI()
     {
 
         for (int i = 0; i <= levelAmount; i++)
         {
             print(getRect(i));
             if (i <= level)
             { // entsperrt              
                 GUI.Button(getRect(i), unlockedTexture);
                 
             }
             else
             { // nicht ensperrt
                 GUI.Button(getRect(i), lockedTexture);
             }
         }
         
     }
 
     Rect getRect(int currentLevel)
     {
 
         int Height = currentLevel * 210;
         int Width = currentLevel * 210;
         int page = 0;
         int temp = (currentLevel - page) / 8 ;
         if(temp >= 0 && temp < 1)
         {
             rc = new Rect(-752 + Width, 296 + Height, 10, 10);
         }
         else if(temp >= 1 && temp < 2)
         {
             rc = new Rect(-752 + Width, 296 + Height, 10, 10);
         }
         else if (temp >= 2 && temp < 3)
         {
             rc = new Rect(-752 + Width, 296 + Height, 10, 10);
         }
         else if (temp >= 3 && temp < 4)
         {
             rc = new Rect(-752 + Width, 296 + Height, 10, 10);
         } 
         else if(temp > 4)
         {
             page = currentLevel;
         }
 
 
         
         return rc;
     }
 
 
 }