Definitely make sure your design system has clear, well-documented guidelines and reusable components. But also build in flexibility so devs can extend and adapt it as product needs change. Figma variants are great for this! And get buy-in across teams early so everyone's invested in making it successful long-term.
To build a scalable design system, focus on clear principles, reusable components, documentation, cross-team collaboration, and flexibility for future growth.
In my opinion, the development of a design system should be approached in the same way as product development:
1. Define the minimum set of components and documentation necessary for launch, along with a development strategy.
2. Gradually bring each component and its associated documentation to a ready state.
3. Conduct user testing. Yes, design systems need this, too.
4. Reuse modules and patterns as much as possible.
5. Keep the design system up to date. Neglecting it even once can make it difficult to get back on track.
A modular system is easily scalable. If you can divide your functionalities into modules with the appropriate directories structure, its the most effective way to scale most of the design systems.