I’m from C# that has the following for your list example:

// If you add an item to this list, it will effect usages outside. You can't reassign it though.
public void Example(List<string> exampleParam)

//Full passing by ref, if you re-assign it to a complete new object, outside usages will be effected
public void Example(ref List<string> exampleParam)

//Output only, this acts as if the method assigned a variable named exampleParam. 
public void Example(out List<string> exampleParam)