I can't think of any examples of that and don't see that in the wars listed above. Destabilized countries are bad news for entire regions and can become havens and recruiting grounds for terrorists, criminals, etc. And those things spread across borders.

The idea that the Iranians will act on his wishes is a fantasy of someone who wants to win without paying the costs, as a freebie.

The current lot in Iran came to power through revolution and they've made very sure that the same thing can't happen to them. The whole system of government, or at least rule, is designed from top to bottom to make as sure as it's possible to get that it can't be overthrown from within. I'm sure Trump's highly qualified expert advisors on the subject, Witkoff and Kushner, told him about this small problem before he launched his attacks.

If think assume too much competence. I'm sure there are various plans (ok maybe not with this "administration", their "plans" seems to be fast-forward grift) but I have very little confidence in them going in any particular direction.