Large TypeScript Open-Source Enterprise Codebases

I'm currently trying to learn Typescript for a few days. A thing that always helps me more than examples of different small use-cases, is looking at a large production-ready codebase of the language.

I browsed through github a bit and found the biggest one's like VSCode or Typescript itself.

Can you recommend any other, more business-like applications where I can learn how to structure really large codebases?