Should pcs be unplugged before restoring power

We have an upcoming scheduled power outage for maintenance.

UPS protects our servers. But it has been suggested that all PCs should be unplugged to prevent damage from power surges when power is restored. Is this precaution really necessary?

In my experience yes. The main problem is that often too many devices are left turned on and create quite a peak when power is back again, with potential damaging effects for the power supplies.

This is the reason why intelligent PDU for server racks often turn devices on in a staggered mode after a power loss.

If you are not sure of the nature of the power outage, I recommend you to turn off the main breaker just before the outage, and restore it just after the outage (isolating your building from utility power, to prevent "short power-on" or any kind of undesired power problems during the outage that could damage something)