[2022] My game changed overnight, how to control "empire size"

Empire Size represents the investment needed to roll out a new technology or tradition across your empire. For example, a one planet empire will need to invest far less into rolling out a new version of a space toaster, than a 100 planet empire will. There is no way to counteract empire size, however, you will get far more benefits from expanding and building more Research/Unity buildings over staying small.