Would it be a good idea?

Hi, I have a very basic understanding of SEO, here's the situation:

I have a website for my social media growth service in french, and I haven't engaged in SEO practices before, but the domain is indexed.

We bought the domain 8 months ago, made a showcase of our services and left it alone, but now we want to change all that to enable customers to order and pay directly from the site.

We are plaing a complete overhaul of the website (new interface, features and languages): the goal now...

Would it be a good idea?