Show products based on category id

I am pulling my hair out. I am trying to show products based on category ID's. but it is showing all products.

In my database, I have a categories table (id =1-60), then I have my products table that has category_id which is the id of the category the product belongs to.

Controller

public function categories()
    {
        if (request()->categories) {
            
            $products = Product::with('category_id')->whereHas('category_id', function ($query) {
                $query->where('slug', request()->category_id);
            
            })->get();

            $categories = Category::with('children')->where('parent_id',2)->get();
        
        } else {
            
            $products = Product::all();
            $categories = Category::with('children')->where('parent_id',2)->get();
        }
        return view('used-equipment/category')->with([
            'products' => $products,
            'categories' => $categories,

        ]);

    }

web.php

Route::get('/used-equipment/{category}.php', 'UsedController@categories')->name('usedequipment.categories');

I cannot for the life of me figure out how to show the product based on the category ID.