Adding a IPV6 address to new interface on Ubuntu 18.04

Question

I recollect not using netplan directly. I had created the file /etc/systemd/network/20-static.network:

[Match]
MACAddress=00:1e:67:d6:33:25

[Network]
Address=192.168.3.83/24
Gateway=192.168.3.81
DNS=8.8.8.8
DNS=8.8.4.4

I want to create a new IPV6 local address and assign it to a new interface with a different MAC address. Should I just append a new "Match" and "Network" section? If so, which command do I run for this configuration to take effect? I do not like netplan to be used directly. I prefer editing some files directly.