Hello together,

I'd like to use lists which create chapters (3 lines) that look like this:

Chapter 1
Title
Subtitle

Chapter 2
Title
Subtitle

...

Title should have a different font and size as subtitle. Is this possible?

You will have to set up three different paragraph styles. Make use of the "Style for following paragraph" setting in the Modify Style dialog box (if applicable).

__________________
Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional

I would urge you to use the built-in styles that come with Word. Note that you can modify these so they look the way you want.
Chapter = Heading 1
Title = Title or Heading 2
Subtitle = Subtitle or Heading 3
Why use Microsoft Word’s built-in heading styles? by Shauna Kelly

If you are starting a major project with Microsoft Word, you owe it to yourself to learn a little about the tools you are using.
Basic Concepts of Microsoft Word - from Shauna Kelly
Understanding Styles in Microsoft Word