The three major global military powers (USA, China and Russia) have all gotten their noses bloodied by a country they thought they could easily beat. USA, take your pick, Vietnam, Afghanistan. Then, Russia, when they were the USSR spent 10 years and in Afghanistan from 1979-1989 and imploded economically trying to house, feed and arm over 200k troops when you already have bread lines back home. It was the first full scale war the USSR fought since WW2 and they took on a country that neither Alexander the Great or the British Empire could completely defeat.
And China actually had a border war with the same Vietnam.
China invaded Vietnam in 1979 and left because the Vietnamese drew them into them jungles and did the same guerilla tactics it did against us. Nobody remembers that.
How the Sino-Vietnamese War Was Purposefully Forgotten China’s People’s Liberation Army (PLA), sizable yet short on fighting experience compared to the battle-hardened Vietnamese troops, made a swift withdrawal. While the major armed conflict lasted less than a month, fighting continued throughout the 1980s. Anyway, it's my belief based on maybe too many youtube videos and conspiracy articles, say that China has pretty much fully infiltrated America's electronic infrastructure and they are capable of shutting down power grids for a whole region like the eastern seaboard. I've read that if it came to push and shove, China's plan would basically shut down the internet via malware, the electrical grid, the access to oil, by disrupting the transportation channels via a few different ways and bets that the American people wouldn't last long without the comforts of life and demand its government end any conflict quickly, no matter what it has to do.
We've only really seen two nuclear powers have skirmishes but they both make sure it never escalates more than border melees tit for tat. Then nuclear powers that have had skirmishes nothing close to ful blown war (yet)
India vs Pakistan in the Kashmir region
India vs China once had a brief border war, nothing higher than shooting and some rockets
China vs Russia border small border skirmishes
China, USA and Russia have mainly fought proxy wars. Russia militarily supported both North Korea and North Vietnam during the conflict, China supported North Vietnam. USA supported Afghanistan against the Russians.
China has no recent hands on experience in war and America has too much, and after two 20 year wars, I doubt the American people are going to get behind any major conflicts that isn't from defending the soil. People aren't going to be falling for the lies (weapons of mass destruction) anymore. The internet has made that extremely difficult. Obama tried to get us more involved in Syria, the people weren't going for it. Biden tried to get us more involved in Ukraine, no one wants that. Israel and the Republicans have been trying to gaslight us into fighting Iran. Now, that's some smoke that ain't gonna happen in terms of land invasion. Non starter.
China wants Taiwan. Taiwan knows its inevitable as well. Matter of when not if they become similar to Hong Kong. More or less as before but media controlled.