2 posts per row? how?

Hi, I’d like to have 2 posts (or even 3) per line of posts, instead of a single one. ie, something like https://www.estoestucuman.com.ar/ where there’s a big main post and then the following posts are in 2 columns instead of post after post.

Ideally, I’d like to have something like

| big post |
|post | post |
|post | post |
| whatever |
|post | post |
|post | post |

I run a news blog and the “post after post” is too “bloggy looking”, I’d like something more “newspapers looking”. I’ve no problems with design and CSS, but I’m very limited at PHP coding, for the sake of it consider me absolutelly ignoramus about PHP.

Anyway, hope you can help me and thank you in advance ??