This question already has an answer here:
Bring it to the second line
This has a number of benefits over the other options:
- No ambiguous titles
- Titles with similar beginnings might look identical when they're truncated.
- Decreased cognitive load
- Searching for a way to reveal the full title will increase the user's cognitive load.
- Maximum length becomes irrelevant
- Sometimes a title needs to be long to provide enough information on context.
- User does not miss out on any important information
- If the title contains information which is important, the user might not see this if the title is truncated.
I believe the only reason to truncate the title is if you're limited for space, such as in the title bar of a window.
However, there does not appear to be any fixed constraints on your title area, so displaying the title on multiple lines is the way to go.