No, you can’t, and it makes no sense honestly to have a feature like that.
If you want , you can use a dictionary, where you can have the key be a string:
Dictionary<string, RectangleShape> shapes = new Dictionary<string, RectangleShape>();
shapes.Add("nameTheKey", new RectangleShape( ... ));
Then you can simply read the “variable” like
shapes["nameTheKey"]
solved Naming a variable based on another variable