Yesterday afternoon President Trump posted the following on X. As Ukraine discovered, power plants are in known locations and hard to defend.
If Iran doesn't FULLY OPEN, WITHOUT THREAT, the Strait of Hormuz, within 48 HOURS from this exact point in time, the United States of America will hit and obliterate their various POWER PLANTS, STARTING WITH THE BIGGEST ONE FIRST! Thank you for your attention to this matter. President DONALD J. TRUMP
Iran probably has backup generators for hospitals and key government buildings, if fuel can be provided.
Without electric power civilization disappears and society reverts to prior norms. Water and sewage don't move, refrigeration ends, heat comes from fire, or sunlight, most homes become little more than artificial caves. Gas stations can't pump fuel, traffic lights don't work, etc. Phones and tablets can't be charged.
Imagine digging a pit privy in your yard, if you have a yard. Carrying water from God-knows-where, cooking over an open fire, and scrounging for light after sunset. Apartment dwellers can't even do this much.
Interestingly, the rural poor will probably be more able to cope than more fortunate urbanites. They are accustomed to living around dung piles and have animals to kill and eat.