Blocking in ipv6 works roughly the same way as in ipv4, just that the scale is different. Instead of blocking something like a company's /24 or an ISP's /16 when they don't respond to abuse messages, you block the company's /48 or the ISP's /32. It'll vary per organisation how large a range they got exactly but you can see that in WHOIS. End users are no longer at a /32 (v4) but at /64 (v6), or some prosumers might have a /29 (v4) and /56 (v6). Same concept, just a different prefix length
Various ISPs give out either a /64, a /56 or a /48. Anything else is very unusual. A normal approach is to limit by /64 at first, limit a /56 to 3-4 times the rate limit of a /64 and a /48 to 3-4 times that again. Someone who has a /48 gets to enjoy 16 times the rate limit of someone who has a /64 but that's not too bad, and you don't have to tune anything per ISP.
Anyone who has bigger than /48 is no longer an individual user. They could be an ISP set up solely for scraping, though that comes with some fees and requirements.
