i have just found a solution to your problem. i myself wanted to display for example CarPark_ID and CarPark_Type on the same label on different lines. using the expression builder, i added the first line "CarPark_ID", and then i added a new entry (click new) and selected Constant button and entered "\n" (without the quotes), and then added "CarPark_Type".
now i get:
all centered neatly. i assume other functions would work as well, and i discovered this only by chance. i think Autodesk should be a little more helpful in their documentation to explain how these functions are possible. best of luck