How to do a layout like this?

By creating a grid e.g. by creating a table, or by using ‘<iframe>‘.
Alternatively you can buy the theme that does this https://www.elegantthemes.com/gallery/aggregate/

Thank you

That site does not use a table grid (outdated way of coding layouts), but rather CSS to “float” each “box” – which lines them up side by side. CSS is also used to style the boxes. More on CSS here:

https://www.w3schools.com/css/default.asp