By ourselves not easily. But such a war is World War III...everyone is getting involved.

Russia has already shown their military is subpar. Ukraine aid has still been quite limited in terms of how much of the more advanced stuff we've been willing to give them and ability to strike Russian targets. They've already got over 500,000 casualties not to mention equipment losses. They're starting with a disadvantage regardless of how Ukraine turns out. Biggest issues from Russia-owned GOPers continuing to detract and otherwise make full support difficult as well as disinformation campaigns.

The middle east is difficult. Question of getting bogged down (as per usual) as well as nuclear concerns. With NATO support on one side and opposing Russia-China support the other. Israel would likely be the biggest ally here(it is a major reason they get military support from us) and already have advanced weaponry and of course genocidal rage. Something something about enemies and enemies.

China would be the most difficult issue if already engaged with Russia and Iran. Numbers and military quality are certainly a concern. All the outsourced manufacturing would also be a major headache, honestly not certain which side would be hurt more by that economically. That said many nearby countries would probably be willing to aid in small and large ways because of dislike of China. Furthermore their last major military engagement was in Vietnam 1979 with skirmishes until 1991. So 30-40y on most Chinese commanders and infantry don't have actual battle experience. So question of quality and whether with allies we could stand up to their manpower and manufacturing capacity.

Not certain how much Africa would come into play as that'd be a real mess.

All in all, winnable or not would only be determined by actual battle. Major losses of life for all involved.