Hi,
the network address has to be set in the guest system, since there is no generic way, to do this for all OS types.
If you want to spend some time on it, you could make use of the qemu guest agent to execute commands inside the VM
and set up your network configuration that way [0].
[0]
https://forum.proxmox.com/threads/about-use-agent-config-ip-address-all-faile.69728/