The US, EU and assorted allies have gradually gotten into the habit, in recent decades, of using targeted sanctions (a lot) against both individuals and govts when the targets do something the West does not approve of.

Do they work? Do they help?

I think Obama-era sanctions on Iran played a part in getting Iran to at least consider the nuclear accord that Trump promptly renigged on ... but I also think Rouhani also wanted to develop a better relationship w/the US (and I'm sure he had at least grudging support from the Ayatollah), and gladly used the sanctions as the justification for speaking to the Great Satan.

Details aside, I think sanctions helped in that case. I can't think of any other examples where they were effective in helping achieve their intended effects.

OTOH, I think aggressive sanctions against North Korea have, at best, done no good at all, and have probably made the situation worse.

Any other successes come to mind?