To build a Design System from scratch, there is this interesting combination of tools: React Aria or React Aria Components, Tailwind CSS for the styling, Class Variance Authority (cva) for the variants, Storybook for the documention. Tailwind CSS is very easy to use and fast to write, and once you get into it, it is so convenient as naming style is no longer needed, that it is difficult to go back to CSS. To create style variants, cva is perfect to combine with Tailwind CSS. And Storybook, to maintain, develop, test and document it.
If you want to try it out, you can find a starter to build a design system with these technologies on my GitHub, thus you don't have to deal with all the set up:
Base-UI