If I ran a dictatorship wanted to create as much destruction as possible I would send out a few different viruses out into a city. Locking off the city from the rest of the country but not to the world. During this time I would ask for stock up on the world's supply of PPE, masks etc. via asking for donations or getting people in other countries to buy it off the shelves and send it through.
These are the viruses I would let out into a city:
I would create one that is a pneumonia similar SARS but make it less dangerous. I will call this virus SARS-Lite.
I would create on