How to define class objects as variables

This is the header file

GeomVisitor.h

// Forward declarations
class Rectangle;
class Font;

class GeomVisitor
{
public:
    virtual ~GeomVisitor() = default;
    virtual void visit(Rectangle&) { };     
    virtual void visit(Font&) { };
};

now in the cpp file i want to create different classes for different objects.

 GeomObject.cpp

   #include "GeomObject.h
  // all other includes

class visitorRectangle : public GeomVisitor
{
private:
    std::string variableName;
    std::string variableValue;
public:
    virtual void visit(Rectangle& rect)
    {
        if (variableName.compare("WIDTH") != 0)
            rect.SetWidth(std::stof(variableValue));

        if (variableName.compare("HEIGHT") != 0)
            rect.SetHeight(std::stof(variableValue));
    }
};



class visitorFont : public GeomVisitor
 {
    private:
        std::string variableName;
        std::string variableValue;
    public:
        virtual void visit(SumFont& fnt)
        {
            if (variableName.compare("TEXT") != 0)
                fnt.setText(variableValue);

            if (variableName.compare("USESHADOW") != 0)
                fnt.setUseShadow(std::stoi(variableValue));

            if (variableName.compare("FONTSIZE") != 0)
                fnt.setFontSize(std::stoi(variableValue));

            if (variableName.compare("SHADOWDISTANCE") != 0)
                fnt.setShadowDistance(std::stof(variableValue));
        }
    };

The problem i am facing is how can i declare class visitorRectangle and class visitorFont as objects in other classes

Do i have to add the cpp files where i need to declare these classes as object varibles ?