The US sanctions are part of a "maximum pressure" campaign on the Iranian government. The US government has banned the rest of the world from dealing with Iran. Therefore, Iran has no exports anymore.
As a result, Iran's currency lost it's value ~10 times in the past decade (When the original sanctions where started by the Obama administration).
The goal of the sanctions are to make people of Iran so miserable that they would go in streets and start a revolution. Now, Iranian people hate the Islamic Republic and would get rid of them if they could. But the Islamic Republic has no limits. They would shoot and kill and many as it takes.
Another challenge for Iranian people and a revolution, except for Islamic regime's cruelty is an unknown future. Iran shares a lot of border with Afghanistan and Pakistan. Iran also has many terrorist groups activated inside it already. That means there are real fears of Isis/Taliban/Other groups rushing to Iran if the central government is weakened.
So people are scared of Islamic Republic, and also scare of what can come next.
Therefore, basically, Maximum Pressure campaign's goal is to make people so miserable, they'd rather face bullets/wars.
This has lead to some really devastating results. Middle class doesn't exist anymore. Some rural cities are reporting that people cannot pay for bread anymore. Most people cannot pay for chicken/meat anymore. Add Covid 19 to this, and a very incompetent and cruel government which has been rendered completely useless by the sanctions, and you get a complete disaster on your hand.
The government is also quite scared, and to make sure there wont be uprisings, is spreading fear. They execute people and hand cruel sentences to everyone. Last weeks they gave a 10 years sentence to an 18 years makeup artist who had a famous Instagram account. Journalists are executed, etc. People's morale are completely shattered.
So the bottom line is, the maximum pressure campaign has rendered Iranian people completely miserable. Even if it were to succeed wit topping Islamic Republic, there is no guarantee that it wont make Iran another Syria situation. Please, as a U.S. voter, I urge you to consider your support for stopping the sanctions.