Comment by montroser

Having both failed and succeeded at this many times in companies from 20 to 1000 people -- here is my advice for you:

Start with the absolute gnarliest, high-traffic, most intricate UIs that are in production now. Design your components to accommodate those most important and valuable use cases, in partnership with the teams responsible for those interactions. If you can handle those, and if you can get those developers to prefer your components because they're easier to work with and they solve the problems the existing tangle is solving, then you will win. Everything else after that will be smooth and easy and it will work.

On the other hand, if you design in isolation, you will likely end up with another beautiful "living style guide and component library" that no one ever uses, because it is not flexible enough to handle real-world interactions, where the designers and product people and engineers all have hard-won legitimate strong feelings about how it all should fit together in the actual product that's making all the actual money.