Thanks for clarifying!
You can have the title on two lines by inserting a line break with SHIFT + ENTER, or by navigating ‘insert’ → ‘Line Break’.
Video
Note that the line break will be visible in the Table of Contents as well–here’s a previous topic on it: https://community.papyrusauthor.com/t/toc-chapters-and-subtitles-formatting/932
I think we can get this done with creating a new text style for titles. 
With a dedicated text style, we’ll be sure that the spacing, font size etc. is consistent throughout all the titles, and once the style is done, it’s easy to apply for any future chapters as well:
Create a new style
- Make a new line of text, select it, and edit it to match how you want the titles to look.
You will be asked whether to change the style here, or everywhere – choose “Change here”. - Once the formatting looks good, open the Styles-dialog with the A-icon from the top-left of the toolbar, and enter a name for the style.
- Select the settings you want the new style to remember (at least Paragraph Format and font size).
- Finally, select the “Enumeration/Table of Contents” tab, and switch the “Hierarchy Level” value to “Level 1 (chapter)”, so Papyrus Author knows that it’s a chapter title style.
- Click ‘Apply’.
Here’s a quick video on the steps:
Video
You now have a new text style for your titles, and you can apply it by simply selecting a title, and switching its text style from the style dropdown menu.
Video
Hope this helps! 