I cannot find a way to start network interfaces with proper config after I changed config files (eg dhcpcd.conf). The only way I found to take the new config into account is to reboot. There must be a more elegant way. Though, service networking restart + systemctl restart dhcpcd.service + ip link set ethx down/up, don't work.
Update with info from comment:
To explain more, I change static ip declarations and don't want to reboot just for that.