Can the Antminer S3 mine Bitcoin using Blake2s algorithm? If so, how? Nicehash can also do this, so what I'm trying to do is point my Antminer S3 to Nicehash's Blake2s stratum. But will changing the stratum URL be enough? Do I have to set up Blake2s first?
No, Bitcoin uses SHA-256 only, BLAKE2s is a different and incompatible algorithm.