About 14 months ago, President Trump reimposed sanctions on Iran. As I remember, one of goals of the sanctions was to reduce Iran's influence in the Middle East by reducing its financial resources.
Are there any results we can see so far?
Any answer will be a bit speculative, because causation is very hard to prove.
Changes in Iran's security and foreign policy since Trump repealed the nuclear deal include the following points:
Tensions escalated sharply in the Hormuz straits with Iran catching several oil tankers, and allegedly attacking others (Iran denies the attacks though). It also shot a US drone which had or had not violated its air space depending on whom you ask. This is one among other drone incidents.
Chi'i militias, including Lebanese Hezbollah, Iraqi groups, and Iranian forces have long provided decisive support to maintain Syria's Bachar El-Assad in power and help him reconquer most of Syria since 2013. Since April 2019, however, these forces, that are widely considered as controlled by Tehran, have refrained from taking part in the attack on Idlib - as a consequence, and in spite of heavy bombing by their other ally, Russia, Syrian governmental forces have failed to make decisive progress so far.
In Yemen, where several rebel Houthi groups are said to be backed and armed by Iran (but probably not controlled by Tehran, or very loosely), some partial truces have been announced last winter but seldom respected.
Once again, how much of all of these possible shifts in Iran's foreign and defense policies have been motivated by the US sanctions is very subjective and I won't claim causation in either case.