RS separates logical "lines" or there is "Group Separator", but for internal line separators in a multi-line text field, the CR and LF characters could be used, because they have "standard" meanings for text:

CR: move next character position to position 1 horizontally LF: move next character position to vertically below current character position, potentially inserting SP characters.

So a combination of CR/LF, or LF/CR would have the effect of "New Line".