Yes you have that right, the network service in CentOS 8 no longer exists. So there is no more systemctl restart network
You can restart NetworkManager but it doesn't have the same effect or ifup/ifdown on all interfaces.
To replicate that the best you can do is type the following commands to nmcli
nmcli networking off; nmcli networking on
*Don't forget the semi-colon otherwise you'll go offline if you are connecting to a remote Virtual or Dedicated Server