If you want to display the text in a new line (Or Newline ) at the text box, the following expression can be used.
=”Line 1 ” + VBCRLF + “Line 2”
Ex : =Fields!AddressLine1 + VBCRLF + Fields!AddressLine2 + VBCRLF + Fields!AddressLine3
Note: If VBCRLF is used first or last part the expression, it has no impact on result. If you want a line in the first or last, then use one more extra VBCRLF.