Great question — answering as the UphillTech team:
Formatting like bold text or italics, in general no - unless some particular SMS providers use a proprietary format for doing this (I'm not aware of any). Standard SMSes are encoded using the GSM 03.38 7-bit alphabet which does include CR and LF (and FF) characters, but how these are rendered is up to the receiving end. Out of the two implementations I have to hand, both just ignore CR or LF (but one of them renders a line break if the message includes two consecutive spaces).
Full answer by user104863: https://stackoverflow.stackexchange.com/a/6494975 (CC BY-SA 3.0).
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