Create or edit /etc/netplan/01-netcfg.yaml and insert the below, replacing the adapter name and IP info if required:

network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: no
      addresses: [10.0.0.2/24]
      gateway4: 10.0.0.1
      nameservers:
        addresses: [1.1.1.1,1.0.0.1]

The example above sets a static IP on my Raspberry Pi.

To restart networking, you can then run sudo netplan apply.