class SalaryCalculator
{
    List<Worker> workers;

    public void PrintWages()
    {
        foreach (var worker in Workers)
        {
            switch (worker.GetType())
            {
                case Worker: // THIS LINE
                break;
            }
        }
    }
    // Other code
}

List<Worker> workers;

public void PrintWages()
{
    foreach (var worker in workers)
    {
        switch (worker)
        {
             case Worker w:
             // w will be of type Worker
             break;
        }
    }
}