Comment by Youden

It's pretty straightforward. On the router (assuming a recent Debian-based distro):

  mkdir /etc/jool
  echo '{"instance":"nat64-minimal","framework":"netfilter","global":{"pool6":"64:ff9b::/96"}}' > /etc/jool/jool.conf
  apt install jool-dkms jool-tools

On a box behind the NAT:

  curl --resolve one.one.one.one:443:64:ff9b::1.1.1.1 https://one.one.one.one

If you want DNS64, 1.1.1.1 and 8.8.8.8 offer 2606:4700:4700::64 and 2001:4860:4860::6464 respectively or you can configure unbound pretty easily.