This article covers method to set up a static IP address on Ubuntu 20.04. Basically, in most network configurations, the IP address is assigned dynamically by the router DHCP server.
The recommended way to assign a static IP address to a device on your LAN is to configure a Static DHCP on your router. Static DHCP or DHCP reservation is a feature found on most routers which makes the DHCP server to automatically assign the same IP address to a specific network device, each time the device requests an address from the DHCP server. This works by assigning a static IP to the device's unique MAC address.
To Get the name of network interface and the default gateway in Linux:
You can either use ip command or the network manager CLI like this:
$ nmcli d