Hey there,
There’s no limit to where you can use Google Typography. Since WordPress gives all posts, pages and even individual posts and pages specific classes and ID’s you can use those selectors to apply your fonts virtually anywhere.
For example, here’s a standard blog post page: https://googletypography.wordpress.com/2013/06/20/google-typography-a-plugin-for-wordpress/
If you wanted to apply a font to the title of that specific post you could use the following selector:
#post-3 .entry-title
OR for all single post pages:
.single-post .entry-title
https://cloud.ericalli.com/image/0W0b2o2V1B3w
Hope that helps!
Thanks,
– Eric