Do firewalls work immediately after installation?

Do firewalls work immediately after installation?
I’m about to start using qubesOS.
however,my Qubes is offline for now because I can’t decide if it’s safe to start using it right away.
Will sys-firewall and dom0 firewall.xml do their job in their default state?
If not, what firewall rule do you think I should set?

imx, yes but in the firewall rule it empty

In the default state, rules block new inbound connections.
All outbound traffic is allowed.
If you don’t want this, configure the rules before you go online.
You will have to take special measures for sys-firewall and sys-net,
using their own firewall tables.

i remember when i install qubes os, i saw firewall rules is empty so i had to configure it

Are you talking of the firewall GUI? - that is only used to control
outbound connections, and is enforced on the upstream netvm…
Inbound connections are controlled by the (ip|nf)tables rules on the qube

maybe so, at that time i’m still very newbie

Do I need to set up a firewall for sys-net as well?
If so, what is the purpose of the sys-firewall?

no, because the firewall is sys-firewall