You’re using GP Premium too right? If so, you can also easily do this through Appearance > Customize > Typography.
See this for reference: https://docs.generatepress.com/article/dynamic-typography-overview/
The selectors for the CSS down below (
time.wp-show-posts-entry-date)may be used as the custom selector for your typography as such: https://share.getcloudapp.com/rRu1b0N7
Nonetheless, If you wish to use custom CSS to achieve this, here is something you may try for the title of WPSP lists:
Here is for the date and excerpt:
Here is an article with regards to adding CSS: https://docs.generatepress.com/article/adding-css/#additional-css
Adding this through additional CSS should work.
Kindly let us know how it goes. 🙂