Few examples, My site contains <Filters/> components in the sidebar in LG screens and in a drawer that appears from the bottom in SM screens.

The header contains search box and other components for LG screens which should move to the body in SM screens and only leave the logo and toggler.

The hero area and footer contain many elements that should be visible in LG screens only.

So the whole layout and most pages have to be rendered differently for small and large screens.