There is however a huge problem with sanctions: you need to have a realistic plan for what you want to accomplish with your sanctions, or else it does little more than adding some friction to trade.
That means that if you want to actually change the behaviour of a nation using sanctions, you need to have modest goals, an acceptance of compromise, and a readiness to let the other side come out looking like a respectable partner. These are basically things the US cannot muster in the relationship with Iran and North Korea, and the American violation of the JCPOA has significantly eroded US ability to persuade other countries to impose their own sanction.
For China and Russia, the US alone cannot impose any important amount of sanctions and have them be upheld by third parties, the USA trying to block all imports from China would just mean the rest of the world needs to switch to using Yuan or Euros because that volume of trade simply cannot be replaced.
https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(nomi...
Russia GDP: ~1.7 trillion
Iran GDP: ~0.45 trillion
North Korea GDP: ~0.028 trillion
Meanwhile, China GDP: ~14.34 trillion
It's just a matter of time before more sanctions arrive. Because dictatorships are short-sighted and incapable of change. So let's say China tries to prod Taiwan with some military approach and fails. Or escalation of border war with India or Vietnam or Japan. Or increasing purchases or Iranian goods.
When there's a mini-war started by China in Asia, you will see a full worldwide sanction on China.