How can I make separate versions of landing page for desktop and mobile devices

Good afternoon, I’m new to WordPress and need to make a Landing page mainly for mobile devices (desktop is secondary). As I understand, if I use responsive design theme, a mobile device will first download the full desktop version page with big size pictures, and then resize it for mobile screen size, thus slowing the download process. Are there any plugins on WordPress that allow to create two separate versions for landing page for desktop and mobile devices? Thank you.