SBC has a great illustration style, and for their property report 2022, I made some new illustrations to fit the content, according to that style.
While it can feel a little constricted illustrating when you already have a set of brand guidelines, it's also very liberating.
I think of it as this: I get to be as creative as I want as long as the look stays within a set frame.
A lot of time I think that is what graphic design is; solving a problem with what you have + some good old creativity.