How do I make my thumbnails and meta look like this?

Hi there,

you will be able to do this in GPP 2.0 - see here:

https://generatepress.com/introducing-the-gp-theme-builder/

Its currenlty in Alpha so we don't suggest using it on a live site - but you can download and start playing with it.. Full release date is expected in around 2 - 3 weeks.