There are no actions the US, EU, Japan & Co. can collective take that will alter China's political system from the outside.
It's why whenever people talk about ganging up on China, they're always extremely vague about it. That's because it's entirely bunk. Do something! What? Something! Do a thing! Which thing? The thing! It's identical to bumper stickers that (used to) say: Save Tibet, it's largely empty virtue signaling or wishful thinking. It's not realistic.
You can sanction them. It does not matter. You can stop all trade with them. It does not matter. They're free standing now, their domestic consumer market doesn't need the US & EU. Their banks don't need outside financing. Their government doesn't need outside financing. Their households have $65-$80 trillion in wealth. They don't require the West's technology trade, they can clone most of it. And so on.
The world population count will add two plus billion people outside of the US, Europe and Japan in the next ~30-35 years. Those people will all do business with China, no matter what the US/EU/Japan do. Those 2.x billion people will represent an economy comparable to the EU.
Trump's Admin took a severe counter-China / stop-China position (as staunch as we'll ever see in the US), it made no significant difference. China is more powerful now than they were five years ago, both economically and militarily. Their share of global manufacturing has never been higher.
Their military can't be opposed anywhere near their borders, they're the world's clear #2 military now, and are increasingly superior to Russia (which can't come close to keeping up in either hardware numbers or technology at this point). At the rate that China's military capabilities are accelerating, they'll easily be twice as powerful militarily overall as Russia within the decade, including having at least four aircraft carriers and a vastly superior space program to what Russia has. Russia will soon be a joke compared to China in military terms (which tells you what the EU is going to look like next to China). So, there's zero threat to pose to China militarily to alter their behavior. The US also has no interest in committing suicide to fight with China, eg over Taiwan. The odds are that Taiwan is already gone, it's just a matter of buying as much time as possible to diversify off of relying on Taiwan for tech manufacturing. The US plan is to make it difficult on China, to add expensive drag to the context, everyone in DC knows the US can't stop China from taking Taiwan if they want it.
And China is going to keep getting stronger in most respects for the next decade or two. During that time Russia will be entirely stagnant, and so will most of Europe. China will tower over everyone except the US (China will have an economy twice the size of the EU given a few decades). The US will be borderline stagnant (average US growth will continue to push toward zero across this decade and next, a long-term trend), as it can't afford its present level of military spending or government spending at all. Meanwhile China's military spending and capabilities will expand while the US capabilities go sideways or contract. China knows all of this, time is on their side.
What's left? Nothing. Attempts would be feeble at best, it would change nothing. We're 30 years past the time to try to flip or contain China, if it was ever possible to begin with. The sole reason to blockade China today (politically, economically), is for your own moral reasons (which is an entirely fine reason), not to try to change China (which isn't possible) or otherwise meaningfully restrict them. The West de facto blockaded Soviet Russia for decades, however that's not what stopped them, that's not what collapsed their system. The West barely traded with the USSR. It took 3/4 of a century for that monstrosity to fail regardless. China's system is at least several times more sustainable at this point than the USSR ever was, and dramatically more potent economically.
Whatever change might happen in China will be of their own doing. Whatever leadership follows Xi will be the next opportunity for the people of China to have a shot at altering their trajectory. That could easily be decades away yet. China is unlikely to ever liberalize, the best you're ever going to get is either Deng Xiaoping or Xi/Mao in terms of authoritarianism; it's for exactly the same reason Russia will never liberalize, there is no other means to hold their territory together other than through authoritarianism, it would immediately begin to unspool otherwise. Things that would not exist organically/naturally (such as the USSR, or Russia's present territory), will cease to exist unless you hold them together through great actions of force. Tibet and Hong Kong do not willingly belong to China, nor will Taiwan, as an example of that in action.