How to display products of all subcategories of a category?

Question

Ruby on Rails

Let's say I have a category "technology", and inside it subcategories ("computers", "phones", etc.). I want to display products from all subcategories of the 2nd category in localhost:3000/categories/2 .
Here is what I wrote for one subcategory, but how to display all products of all subcategories?

def show
  category = Category.find_by(id: params[:id])
    	subcategories = category.subcategories.first
    	@products= subcategory.products
end

The only thing that comes to mind is using each to add to the array and then output it, but there may be another way