No, this extension converts all anchor links that are on the page that the extension runs on. So you do not have to make any changes to existing pages. Just select a module position(for instance debug) and publish the module to the page you wish.

KB Article: https://loginsecure.eu/helpdesk/knowledgebase/view-article/99-loginsecure-smooth-scroll-can-i-still-use-default-anchor-links-or-do-i-need-to-do-something-special-to-make-it-work