Get data multiple category id with whereIn

get-data-muntiple-category_id.php

<?php
public function index($slug)
    {
        $parent = Category::where('slug', $slug)->first();
        $child = Category::where('parent_id',$parent->id)->get();
        $category_id = $parent->id;
        $child_array_id = [];
        foreach ($child as $key => $value) {
            $child_array_id[$key] = $value->id;
        }
        $count = count($child_array_id)+1;
        $mix_cat_id = $child_array_id[$count] = $category_id;
        
        $reviews = Review::whereIn('product_id', function($query) use ($child_array_id){
            $query->select('id')
            ->from(with(new Product)->getTable())
            ->whereIn('category_id', $child_array_id);
        })
        ->orderBy('created_at', 'desc')
        ->paginate(5);
        
        return view('app.categories.index', compact('parent', 'child', 'reviews'));
    }