The common wisdom is that BGP serves /24 prefixes for IPv4 and /48 prefixes for IPv6. However, this is more of a convention, than a hard rule. Larger prefixes are observed in BGP routing tables.

This website summarizes a paper about hyper specific BGP prefixes. It shows how common hyper specifics are over time for IPv4 and v6.

Hyper-Specific Prefixes on the Internet