That's not what we're seeing with nuclear power though. At least so far. Counterintuitively it seems to get more expensive the more you build of the same design: [1]

> Among the surprising findings in the study, which covered 50 years of U.S. nuclear power plant construction data, was that, contrary to expectations, building subsequent plants based on an existing design actually costs more, not less, than building the initial plant.

[1] https://news.mit.edu/2020/reasons-nuclear-overruns-1118

Mass production has never been tried before for nuclear so those 50 years don’t tell us much about the possibilities for the next 50 years. They built multiple mainframes of the same design too, but the scale remained tiny and so the costs remained high.