Step 1 – Download Owl Carousel from the website – https://owlcarousel2.github.io/OwlCarousel2/
Step 2 – Include Owl Carousel CSS and Js Files in Theme Functions file – functions.php
wp_enqueue_style( 'owl-carousel', get_stylesheet_directory_uri() . '/css/owl.carousel.min.css' );
wp_enqueue_style( 'owl-theme', get_stylesheet_directory_uri() . '/css/owl.theme.default.min.css' );
wp_enqueue_script( 'owl-carousel', get_stylesheet_directory_uri() . '/js/owl.carousel.min.js', array('jquery'), '1.0.0', true );