Let's be real.And even for the big players, if you actually look at the WWIII plans from the end of the Cold War, those still rely on massive drafted armies and i wouldn't be surprised at all if the current, still secret WWIII plans Nato or China have in their files still do.
World war 3, had it happened (as it nearly did several times) would have and still would be over in anything from a week to a few hours, at which point a significant proportion of the planet's population would be dead. Many more would die of starvation over the subsequent decades. Human civilization would be forever changed. A conscript in such a war would probably not even have time to receive their draft orders, let alone reach any kind of front. In the unlikely event anyone did reach a front, the situation there would be abject chaos as the nation which sent them there would, in all likelihood, have ceased to exist. Their commanders would be dead or cowering in a bunker somewhere.
All of the world war 3 plans operated on the assumption that the war would escalate to the use of nuclear weapons. They operated on the assumption that supply lines would be destroyed, command and control would break down under the sheer scale of destruction and that most of the civilian population would die. When ground forces appear in such plans at all, they take the form of a highly mobile professional army racing ahead to capture irradiated wasteland cleared by tactical nuclear weapons as quickly as possible in full knowledge that they are never going to be resupplied or reinforced. Even here, the plans are ludicrously optimistic.
The concept of a winnable third world war is absolutely absurd. It's the pinnacle of cold war delusion. We shouldn't be indulging it.