How to cast a List

I have a variable of List<Tbase>. I know that all items in it are of TChild. I have this TChild type only as a variable similar to var t = typeof(TChild).

So I tried:

                     var elementType = param.ParameterType.GenericTypeArguments.First();
                     var values = value.Select(x => Dynamic.InvokeConvert(x, elementType, true)).ToList();

Yet It gives type 'System.Collections.Generic.List1[System.Object]' white I need it to be of target type.

So how to cast a List<TBase> to a List<TChild> using reflection (not using Linq Cast<>)?