The `randombytes_deterministic()` function from libsodium or libhydrogen does exactly what the name suggests.

Libbsd includes it.

https://libbsd.freedesktop.org/

Monocypher is a decent fit here. Just run its ChaCha20 with (a hash of) your seed as the key. Larger libraries (libsodium, NaCl, etc) are decent too, but bigger.