I'm sure not all young people are buying into the official propaganda.
Unfortunately 80%+ approval rating for Putin shows that most of the people, including young ones, are believers in the same state-produced message: fear and caution, revisionism, nationalism, conservationism, etc, etc.
And the subject of WW3 is discussed quite frequently, on talk shows on state tv channels.
Also to be clear I don't mean that no one affected by propaganda. Pretty sure that like 70% of people may actually agree on many things shocking for average european.
Though very few of these brainwashed people will actually go defend Putin regime in case something happen. Likely it's about the same amount of people you may see participate protests in past years.
I don't think Russian soldiers think differently.
Sadly I can't tell the same about other parts of country population because there is huge amount of older people that don't have a job (and have absolutely no way to get one because in Russia nobody need you once you're older than 40) and of course they have nothing else to do than get drunk and watch TV. It's also a lot easier brainwash people that had no life, have no money to live like in US / EU and have no future.