I don't necessarily think so. It's just a question of political will.
To conquer Philippines or Japan, you'd be looking at deploying a bare minimum of 1 million soldiers each, and the ensuing campaign.
It's not worth it, if the alternative is a negotiated settlement because they have been successfully blockaded, which is far easier.
Even if you assume 1:1 gdp to warfighting capability between China and US, that still means China can put put 1.3x as much military hardware power. And China has tons of manpower.
In a US-China conflict, it will be a primarily a naval-air war, where manpower for the Army is not an issue. But there are 2 caveats to this statement.
1. A naval-air war will be fought by the respective industrial bases of China and the US, where skilled manpower is very relevant.
2. I'm assuming that there won't be a war on the Korean peninsula, where the Chinese Army traps the US Army into fighting a land war, where the Chinese Army will have the advantage. I used to think this was more likely, but I don't think China has to resort to this anymore, because it can now win an air-sea war through Chinese industrial might. As per the US Navy briefing which states China has 232x the shipbuilding capacity and also the US Air Force briefing which states a 4x weapons development speed advantage and a hypersonic missile cost advantage of up to 20x.
In ww2, Japan took Philippines in 1 year, despite bungling the campaign. They took Manchuria (comparable population size to modern Japan) in 5 months. At its peak, Imperial Japan was roughly peer to the United front. Whereas modern China greatly overmatches modern Japan.
A war over Japan and especially over the Philippines needs not necessarily be a long campaign. China's dominant industry means that once the skies are open, they can nearly earmark 1 bomb each for every single person in say the Philippines. It's something even US at its height couldn't do, except for tiny countries like Panama.
Morale will crumple, and it's very likely that a goal target of of 5 months to 1 year can be repeated.
From a perspective of "can it be done", military subjugation of Philippines and Japan is possible, assuming wartime mobilisation by China.
Where it becomes much less certain is if the near peer US can throw 100% of its forces and fully mobilise to stop China in Asia.
From China's side, the current government would forbid it's national power to be used in this way, but we can't know if a future Chinese admin would feel pressed enough that it needs to attack. And in that case, the ability to achieve it is there already.
But is it worth it?
Let's take an upper-case scenario for Philippines and Japan
a) 1000 Chinese cruise missiles per day (as per the CCTV newsreel documentary)
b) Then presumably add a minimum of another 3000 Shaheed-type cruise missiles per day, because they are so much cheaper than a high-end cruise missile, plus China will have spare motorcycle engine and CNC machining capacity to do this.
That is 120K aimpoints per month, just from these 2 systems.
You're looking at total industrial and economic devastation in Japan and the Philippines.
For example, the electricity grid is gone. The airports and seaports aren't operational.
Does China really need to invade Japan or the Philippines? Or would they decide to ditch the US alliance
