How to automatically load more data when users reaches at the bottom of the page of the wordpress site?

You can run an ajax request when user hits the bottom of the page

if($(window).scrollTop() == $(document).height() - $(window).height()){
//your ajax request
}

the link to ajax rquest
https://codex.wordpress.org/AJAX_in_Plugins
for how to add data
https://rudrastyh.com/wordpress/load-more-posts-ajax.html
instead of loadmore button you can paste your ajax request in the if condition

tech