How to structure the layout?

Hi,

I would like to improve the design of our (blog) pages of the content part (main structure), not the header or footer, of the website. See in the private area the page that I would like to redesign.

See the following example page that I found to show you what I mean: https://teamdigitaal.nl/marketing-automation-functionaliteiten/.

What I'm looking for is the best practice to build such a page with an main content area and a smaller side bar.
Do I need use a grid or ...

If you have an idea for a more modern example, then that would be even better.

Thanks Henk.