vi /etc/docker/daemon.json
{
  "ipv6": true,
  "fixed-cidr-v6": "fd00::/80",
  "experimental": true,
  "ip6tables": true
}

systemctl restart docker

test

docker run --rm -it busybox ping -6 -c4 ipv6-test.com
docker run --rm -it busybox ifconfig