Masonry: small and big posts?

Hello everyone!

I need your help, I’m just an amateur coder but I’d like to costumize my theme.

I’m using one with the masonry grid layout, which I love, but the previous theme I was using also had the possibility of big posts. That means that when I toggled the possibility in the Edit Post, the post was twice as big on the homepage.

Would you be that kind and help me integrating this function to my new theme too?

Thanks!

P.S.: I’m using Outspoken by WPShower.