What to do as SEO Specialist, holistically?

So I got an offer as an SEO Specialist, as a side note I start my career from copywriting, content writing, then as an inevitability I got SEO knowledge. In my previous work, I kind of developed the SEO Content from ground up, using some basic technical SEO knowledge and keyword research to develop content from, building the traffic literally from 0.

Now that I'm probably gonna start a proper SEO Specialist role, what's the checklist that's gonna help me or everyone that is going in this path? Thank you in advance.