How to control text case

Hi. I want to be able to control the case so not everything is upper case in the title headings for posts, pages and particularly the sidebar widget title headings. In other words, be sentence case?

Is there a way to do this, maybe with css in the child theme? Or, possibly a modification in the Theme Option settings that I missed?
Thank you.

This is my site:
https://www.hersheylibrary.org