c++ - Benefit of declaring class as pointer?

I know there had been a discussion similar to this in the past but answers appear to be outdated in my opinion. Most say that the differences are the following:

1. Scope - since on the old questions ask with examples of these objects declared inside the method instead of as a member of the class.




2. Safety from memory leak - old questions use raw pointers rather than smart pointers

Given my example below, class Dog is a member of class Animal. And is using smart pointers. So the scope and memory leak are now out of the picture.

So that said.. What are the benefits of declaring a class with a pointer rather than a normal object? As basic as my example goes - without considering polymorphism, etc.

Given these examples:

//Declare as normal object
class Dog
{
public:
    void bark()
    {
        std::cout << "bark!" << std::endl;
    }
    void walk()

    {
        std::cout << "walk!" << std::endl;        
    }
};

class Animal
{
public:
    Dog dog;
};


int main()
{
    auto animal = std::make_unique();
    animal->dog.bark();
    animal->dog.walk();
}

And..

//Declare as pointer to class
class Dog
{
public:
    void bark()
    {
        std::cout << "bark!" << std::endl;
    }
    void walk()

    {
        std::cout << "walk!" << std::endl;        
    }
};

class Animal
{
public:
    Animal()
    {

        dog = std::make_unique();    
    }
    std::unique_ptr dog;
};

int main()
{
    auto animal = std::make_unique();
    animal->dog->bark();
    animal->dog->walk();

}