US does a good job ruining itself without PRC intervention lol. Just trading and constantly borrowing from China adds to it. The 'multi-polar' world rhetoric by China/Russia and their allies is inherently about how to manage as the US declines on the world stage. Sec of State Blinken has been disrespected in his foreign visits numerous times (including by the Chinese) as a sign of this.
The Chinese intend to reduce US influence in the Pacific and it appears that if there is a confrontation it will be in the naval sphere. They have developed anti-ship weapons and are engaging in a historic ship-building program as if they were preparing for WW3.
The US military has a recruitment crisis, due to low desire for young people to join a failed military lead by a failed political class combined with the lack of physical fitness of actual recruits. It is currently reorganizing for large scale warfare after two decades of counter-insurgency..
If we see what's going on in Ukraine it is quite bad these days for anyone willing to join the military to fight a potential WW3 and rein-act Call of Duty. Unless you get a support job, if you are a frontline soldier there is little glory to be had.
The overwhelming majority of Tanks and IFV are getting destroyed many miles away with artillery and PGM without contacting the enemy... infantry getting harassed by enemy drones all day long.