can someone help me edit function in codeigniter 3 to codeigniter 4 ?

I'm learnning the instructions on the website AJAX CODEIGNITER 3 but they guide on codeigniter 3 because it's very difficult to convert to codeigniter 4. I hope, someone can help me convert this code to codeigniter 4

i write it again blow but dont work for me, can you edit help ?

PHP Code:

function makeQuery($minimum_price, $maximum_price, $brand, $ram, $storage){
  $builder = $this->db->table("product");
  $builder->where('product_status', '1');
  if(isset($minimum_price, $maximum_price) && !empty($minimum_price) &&  !empty($maximum_price))
  {
  $builder->where('product_price', $minimum_price);
  $builder->where('product_price', $maximum_price);
  }
  if(isset($brand)){ 
  $brand_filter = implode("','", $brand);
  $builder->whereIn('product_brand', $brand_filter);
  }
  if(isset($ram)){
  $ram_filter = implode("','", $ram);
  $builder->whereIn('product_ram', $ram_filter);
  }
  if(isset($storage)){
  $storage_filter = implode("','", $storage);
  $builder->whereIn('product_storage', $storage_filter);
  }
  return $builder;
    } 


I edit code again, it work, so i note someone need