You can create a multiline title with specific line breaks in a PDF output.
Note:
If your publication is being translated, you must add a line break at the end of the mainbooktitle after the last word. This has no impact on your outputs but it provides a placeholder line break for localization that they can move if they need it for a translated version of the output.
If your publication is being translated, add a line break at the end of the mainbooktitle after the last word. Adding a new line does not impact your output, but it provides a placeholder line break for localization. The localization team can move if additional space is required for a translated version of the output.