I doubt that most consumer routers expose this functionality. IPv6 NAT is rarely needed and should be avoided. Interestingly enough I stumbled upon a use case today. No IPv6 connectivity at my office but at my dad's house. Since a WireGuard tunnel is layer 3 I can't use router advertisements and the prefix is dynamic, so private IPv6 addresses and NAT66 it is. It was an exercise out of curiosity though, route64.org works much better for IPv6 connectivity.