It will have to be by force and that means some form of prison. However it doesn’t mean literaly throwing people to the gulag. This isn’t an endorsement of Scandinavia at all given social democracy is only possible because of imperialism, but you can see that even today it is entirely possible to build better prisons that help people integrate into society, this is a good example in Norway.

So instead of teaching the lib shit it would be socialist literature, marxism etc.

China has to deal with not just re-education but religious extremism and that is much tougher because religion is very hard to refute with just “facts and logic”, it can require a lot of personal effort to abandon religion and admit you were wrong or even to admit the people you admired to were simply exploiting you, also the amount of people they have to deal with is not trivial. Here you can check out the actual Uyghur prisons from the BBC visit years ago

The ideal communist world would definitely be closer to trying to create small re-education communities where people will be forced to spend time learning(as long as it takes)while also not becoming completely useless and detached from society, in fact the re-education should include the opportunity to learn new skills as motivation and again to avoid becoming detached from the outside world.

The actual gulags would be most used during the early stages of the revolution and reserved for people that are truly hopeless or not worth the effort like capitalists(billionaires, executives, investors) a decent portion of the already radicalized alt-right, lots of right wing politicians etc.