A method for generating 2k bits of randomness from k bits of seed is Goldreich-Goldwasser-Micali (GGM). It is used in MPC and game theory as a protocol for generating random outcomes fairly and securely by multiple participants without a trusted third party.
Reference
https://medium.com/zkpass/introducing-the-hybrid-mode-of-zktls-a-zkpass-innovation-9ec18b36f397 https://crypto.stanford.edu/pbc/notes/crypto/ggm.html https://blog.chain.link/realizing-spvole/