You can add line breaks to shape and connector labels.
Press Shift+Enter as you type the label text to add a line break.
Line breaks are only possible when you use HTML labels, and with word wrapping enabled on shapes. Both are enabled by default.
Re-enable HTML labels and word wrap
If you find a shape or a connector doesn’t allow you to add a line break, edit the shape style to re-enable these two options.
- Select the shape, then click Edit Style in the Style tab of the format panel.
- Add the style options: whiteSpace=wrap and html=1, as shown in the image below.