inverter power

please i need to know in due time, if you are building an inverter, which component varies the current to set the power, am making an inverter and i want to know if it is the transformer or the transistors that set the wattage of the inverter and how

Most inverters have a push-pull voltage boost driver. When load is light the duty cycle of the primary side switching transistors are reduced.

The power capability of inverter is determined by the size of switching transistors and size of transformer based on the switching frequency.