I searched that there is a code for Twig that is something like {% if is_mobile() %} that can check if the viewport size is at mobile size. But it does not seem to work on October with error Unknown "is_mobile" function.

Is there a way to track it? I want exactly something like that. Thanks a lot!

Why not create your page with all the things you need for mobile and desktop views but then use media queries to hide/show what you need. You could also use bootstrap's visibility classes as mentioned here http://getbootstrap.com/css/#responsive-utilities-classes

Understoof. Thanks a lot for your response!