A redesign is worth it when the site is slow on phones, hard to edit, built on software nobody maintains any more, or no longer says what the business does. It is the wrong first step when the site is fine and simply isn't being found. In that case the fix is usually better content and technical SEO on the pages you already have, which costs less and carries no migration risk.
Before we quote, we look at the site and, if you can share it, your Search Console data. Then we tell you which of the two you need.
What we need from you is small: access to the current site and its hosting, Search Console and analytics if you have them, and the people who can approve content. What you get is a design signed off page by page, a rebuilt site on a staging address you can click through before launch, a written redirect map, and a launch checklist with every item ticked. After launch you keep the code and the content.