How can I iterate over variadic template parameters in c++?

I'm trying to use variadic templates (for the first time really) to make a string replacement function.

Essentially, I want to make a function (we'll call it Replace) that takes a key value that is used to search up and modify a template string based on the additional parameters provided in the Replace function. The template string has placeholders using the string "%s".

My problem is, I'm not sure how to iterate through the variadic template parameters... Here is some sample code.

const std::string FindOriginal(std::string Key)
{
    if(Key == "Toon")
    {
        return "This is example %s in my program for Mr. %s.";
    }
    
    return "";
}

std::string Replace(std::string OriginalKey) {
    return "";
}

template<typename First, typename ... Strings>
std::string Replace(std::string OriginalKey, First arg, const Strings&... rest)
{
    const std::string from = "%s";
    std::string the_string = FindOriginal(OriginalKey);
    
    int i = 0;
    size_t start_pos = the_string.find(from);
    while(start_pos != std::string::npos)
    {
        // Ideally here I can somehow get the parameter at index i... 
        the_string.replace(start_pos, from.length(), rest[i]);
        
        start_pos = the_string.find(from, start_pos);
        i++;
    }
    
    Replace(rest...);
    
    return the_string;
}

int main()
{
    std::cout << Replace("Toon", "5", "Jimmy") << std::endl;    
}