Stacking Labels characters Question?

I need help to find information about how to use stack separators for words. I am GIS Specialist and I work with maps. I have some maps that I need to split the words to create stack two lines.

Are there stacking separators online that can I find that can help me out ?

Here is the example of what I am taking about:

Here you see the pictures that I need to put Stacking Separator input so the text can split to make the Stacked Labels into two lines ?

I am using ArcGIS Desktop 10.5.1 .