Reference data types maximum range for each variable

You don't seem to understand what a reference type is: it doesn't have a "max range" in the sense you seem to think.

A reference type is restricted by the Heap, not by the type: a string does have a "range", it's an immutable value with a theoretical maximum length of 2,147,483,647 characters in theory (because it's Length property is an int value, and that's the largest value it can hold. Similarly, the Length property of an array is also an int - but .NET had a maximum allocation size of 2GB prior to .NET 4.5 so no single object (and an array is a single object) can exceed that. Post 4.5, it is possible to get 4GB objects in 64 bit systems, but even that won't allow you an array containing 4G worth of values in most cases, because very few value types are less than 8 bytes, and an array of references is always going to be 8 bytes * the number of elements in the array.

The "range" of an object is undefined because everything is an object even if it's a value type - so object has no fixed size at all.