First of all log in to your WordPress site and click on Settings >> Discussions then go to Other comment settings section.
Now search for Break comments into pages option. Here you have to enter a number (how many comments you want to show in the first page) to break your comment.
Click on the Save Changes button to store your settings.
Comment pagination has a negative effect on your website SEO. WordPress generates a URL for each comment page. When you click on the second page of the comment, that page looks the same as the first page.