How to use void pointers/typecasting for implementation of a doubly_linked_list class

I have an assignment in which I have to implement a doubly linked list ADT. I do not have issues with that, I created something like this:

class DoublyLinkedList{
    struct Node{
        int value;
        Node* next; 
        Node* back;
    };
    Node* head;
    Node* tail;
    int count;
    Node* GetNewNode(int data);
    Node* NodeByIndex(int index);

public:
    DoublyLinkedList(){
        head = nullptr;
        head = nullptr;
    }

    // and then all the member functions. I am not including here the definitions, just declarations

    void insertFront( int data );
    void insertRear( int data );
    int removeFrontInt();
    int removeRearInt();
    int size( );
    void makeEmpty();
    void print();
    bool insertAt( int data, int index );
    int removeAt(int index);
    int findIndex( int data );
};

int main(){
    DoublyLinkedList list;

    list.insertFront(1);
    list.insertFront(2);
    list.insertFront(3);
    list.insertRear(100);
    list.insertRear(200);
    list.insertRear(300);

    std::cout << "List: " << "\t";
    list.print();
    std::cout << "Size of the list: " << list.size() << std::endl;

    std::cout << "Removing first number in the list... " << std::endl;
    list.removeFrontInt();
    std::cout << "Removing last number in the list... " << std::endl;
    list.removeRearInt();
    return 0;
}

The professor included an optional section of the assignment:

As an option if you want the list to be more useful you can have the node accommodate a pointer to a void instead of an integer. Then you can store any data not just integers provided you push and pop a pointer to the data and not the data itself. If you make this change then you can add the following functions.

void insertFront( void *data );
void insertRear( void *data );
void * removeFrontPtr( );
void * removeRearPtr( );

and make the data a pointer to a void as opposed to a simple integer. To insert and remove an object you will use the following. Given the following declaration:

Class SomeClassType someObject, *ptrToSomeObject;

To insert pass the address of the object:

insertFront(&someObject );

To remove type cast back to a pointer to the original data type:

ptrToSomeObject = (SomeClassType *)removeFrontPtr( );

You can adapt the Option1 functions to use void pointers as well. Note there are no points for this part as this is only if you feel like you want a more useful list class for your future library.

I am lost with this. I have no idea how this would work, because, for example, don't you need to know the data type of the user input to typecast it? I just really have no idea. Any help is appreciated, even is it is a link to an article or a video, or just an explanation.