Schooling before age 18 is compulsory.

Just remove the age limit. Easy.

A sloppy analogy without a lot of details that just popped into my brain, I think of it kinda like a military’s basic training camps/bases/postings.

You take a group of people and sequester them in a place where they’re under a fair amount of observation and sheepherding. A pretty set mandatory routine, ideological education, basic education, technical education, exercise, free time, meals, personal hygiene, sleep. As time passes and the opinions of the educators/trainers as well as any objective measures that could be developed would give the re-educated person the opportunity to move on to different areas where there are gradually less restrictions until it is decided that the folks can be allowed back into society. Transition and placement services for the “graduates” should exist to aid these new members of society.

Those that fail, can just stay in the system until they pass.

Those that refuse can just be kept in the system until they get tired of refusing or until they get to an age that it can be considered of little risk to allow them back into society.

And what would be done about those who don’t want to learn?

Rephrase this as something like, ‘what about those who just don’t care about anyone but themselves?’ and the answer becomes pretty obvious. Enjoy the gulag lol. China also showed that even terrible people can be rehabilitated. And most of the shitty people in western societies have been conditioned\socialized to be that way cause its the only way to “get ahead” or lately survive under capitalism. Change the conditions change the people.

Torture and executions obviously

There is no such thing as non-coercive coercion. Coercion is not necessarily bad, especially when coercing people into being good.