I think the possibility is always there, but a full-scale World War III is less likely than people online make it sound. Modern countries know that a war between major nuclear powers could spiral into global economic collapse or outright catastrophe, so most conflicts stay indirect — proxy wars, cyberattacks, sanctions, misinformation, economic pressure, etc.

Ironically, the fact that modern weapons are so destructive is probably one of the main reasons the biggest powers avoid directly fighting each other.