Maintaining SEO While Updating Pages?

So I'm going to be updating a client's site from some defunct block-style builder (Enfold) to Elementor in the coming days, it's basically outdated to the point where updating PHP completely breaks the site. Anyway the page content/images, etc. will be the same on the updated pages, just wondering if I edit the existing URL pages after updating will it have any negative effects on SEO? Or would I be better off making new pages then 301 redirecting back to the old URLs?