Start by preparing the caramel sauce. In a saucepan over medium heat, melt the granulated sugar until it turns into a rich amber color. Carefully pour the caramel into your flan mold or ramekins, swirling to coat the bottom evenly. Set aside to cool and harden.
In a mixing bowl, whisk together the eggs, sweetened condensed milk, evaporated milk, and vanilla extract until well combined.
Gently pour the egg mixture into the flan mold or ramekins over the caramel layer.
Cover the flan mold or ramekins tightly with aluminum foil. This prevents water from seeping in during the cooking process.
Pour 1 cup of water into the Instant Pot. Place the trivet inside and carefully set the flan mold or ramekins on top.
Seal the Instant Pot and set it to "High Pressure" for 25 minutes.
Once the cooking time is up, allow a natural release for 10 minutes before carefully releasing any remaining pressure.
Carefully remove the flan mold or ramekins from the Instant Pot and let them cool to room temperature.
Refrigerate the flan for at least 4 hours or overnight to allow it to set.