Traditional SEO retainers usually cap out at 30 percent margins, but...

https://www.pop-bookmarks.win/most-agencies-stay-stuck-at-30-percent-margins-trapped-by-the-service-model

Traditional SEO retainers usually cap out at 30 percent margins, but productizing your internal scripts can get you past 70 percent. Treat your agency like a lab to build tools that solve real problems, then sell that software as a scalable product.