Change the font of the blog posts widget title

i had to see the page it concerns.
if it is similar to this:
https://kriesi.at/themes/enfold-2017/blog/blog-multi-author/ or
https://kriesi.at/themes/enfold-2017/blog/

Or do you mean the single blog post? – it only differs in the heading tag ( h1 or h2 ) so this might work on both cases:

#top .template-blog .post-title.entry-title {
  font-family: "Times" !important;
}