Is modifying a function in derived class and accessing it by derived class object itself an example of runtime polymorphism

I was reading about function overriding and run-time polymorphism online.

While reading I found an example of function overriding on programiz where following example was given :

// C++ program to demonstrate function overriding

#include <iostream>
using namespace std;

class Base {
   public:
    void print() {
        cout << "Base Function" << endl;
    }
};

class Derived : public Base {
   public:
    void print() {
        cout << "Derived Function" << endl;
    }
};

int main() {
    Derived derived1;
    derived1.print();
    return 0;
}

Output

Derived Function

Here in Derived class we have modified print() function of Base class and is accessed by an object derived1 of the derived class.

A question stuck in my mind - is this an example of runtime polymorphism also? or operator overriding not always comes under runtime polymorphism as I have read this somewhere

The main use of virtual function is to achieve Runtime Polymorphism.Runtime polymorphism can be achieved only through a pointer (or reference) of base class type.

Hence my question is - "Is this an example of run-time polymorphism as does not use the virtual keyword and involves a pointer to base class and even an example of function overriding?

Correct me if I have mentioned anything wrong.