How can we simplify this switch expressions in C#?

Question

Here is a switch function:

public static void Main(string[] args)
{
    int level = 5;

    var indicator = level switch
    {
        1 => "C",
        2 => "R",
        3 => "R",
        5 => "R",
        6 => "R",
        _ => "D"
    };

    Console.ReadKey();
}

Here all the 2,3,5,6 will return the same result "R", I try to add the key word "or", but there will be a Compile Error. Is there a way to simplify it? thanks.

public static void Main(string[] args)
{
    int level = 5;

    var indicator = level switch
    {
        1 => "C",
        2 or 3 or 5 or 6 => "R",
        _ => "D"
    };

    Console.ReadKey();
}