Depends on your demographics a bit. Dictatorships like to scapegoat ethnic minorities or other out groups (see Pinochet’s, Mao’s, Pol Pot’s, etc extermination of scientists and educators) for society’s problems. These groups of people tend to experience much greater intensity of oppression under dictatorships than already present in the US. This tends to change culture on a fundamental level because most people actively try to fit in with the in group to avoid becoming a target themselves.

While present to some degree in our current system, another core characteristic of dictatorships is that self enrichment for those in power is the primary driving factor for decision making. Dictators don’t need to pay lip service to making decisions for the greater good. You see this especially prominently in dictatorships in developing countries with valuable resources… The dictators and their close friends take all of the wealth from resource extraction for themselves and everyone else lives in extreme poverty. Yes we have wealth inequality already, but it would be accelerated even more. You could see even highly skilled professionals having a hard time making ends meet (or in jail for being too smart and having “ideas”), and even more homelessness, potentially even wide scale famine.

In terms of geopolitics… Our relationship with allies would become about how the relationship personally benefits those in power.