Here're the examples of two column website layouts for tablets (portrait and landscape), desktops and large desktops.
These layouts will become horizontal i.e. changed to one column layout on mobile devices.
Here're the examples of three column website layouts for desktops and large desktops as well as for tablets (e.g. Apple iPad) in landscape mode.
These layouts will become horizontal i.e. changed to one column layout on mobiles and tablets in portrait mode.
Here're the examples of multi-column website layouts that will change the column placement and/or sizes depending on the device viewport width.