No; most sites I reach from the phone seem to be reached via IPv6. E.g. hitting whatismyip.org exposes an IPv6 (though mentions an IPv4 because they're trying to discover that, too). Some sites do not support IPv6; for those indeed there's a XLAT464 service.

464XLAT is for dealing with IPv4 literal addresses in a v6 only network. Non-literals can be addressed with DNS64 & NAT64