Here is an example:
Edit /etc/network/interfaces
It’s best to make a backup first
cp /etc/network/interfaces /etc/network/interfacesbackup
iface eth0 inet static
address 192.168.0.16
netmask 255.255.255.0
gateway 192.168.0.1
Set the DNS server in /etc/resolv.conf,
nameserver 192.168.0.1
#Since my gateway is also the DNS server here, they are the same
Finally, reboot or run #/etc/init.d/networking restart

My own approach:
Originally, my machine used DHCP to dynamically assign the IP, so it was written like this
iface eth0 inet dhcp
I copied the original interfaces file to interfaces.dhcp
Through the modification above, I copied interfaces to interfaces.static