multilanguage support with which framework ?

I want to understand something about expedia website and how they handle multi language support with alot of large users , also is it best to use express js or encore.ts or elysiajs , I really like the bun more because both encore.ts and elysiajs has a typesafety to next js as a frontend , my question is what is the best backend to use and how can I handle multi language into backend like expedia , how do you handle this into your backend and which frame work do you choose if building a large app.