I think the most important thing will be for you to define your role.
I’d outline that in a document, for your employer, but more importantly for yourself, and then identify a few opportunities that align with that document that could be quick wins and knock those out in the first couple of months. It is important to establish momentum.
The company I’m working at now had various industrial and graphic designers but they never had a design leader. The first thing I did (before I even started) was outline my vision for my role, a mission statement for my team, and what the first few projects would be. Coming in with a sense of purpose is huge.