The Iranian nuclear deal, until some stable genius ripped it appart.
It definitely put pressure on Rhodesia and South Africa, both of which eventually experienced regime change.
No idea about Rhodesia but for SA I think it was mainly doing of ANC
Cast your mind back to WW2, where the Allies' sanction of Japan basically set the wheels in motion for their collapse.
Sanctions are not designed to change the regime. Look at the French president complaining how it’s “not fair” the the US seize the moment to lure European manufacturers to the USA.