The Big Mac today is essentially unchanged from its introduction, aside from changes in ingredient quality. It's the same size and has always used the small patties that they use in their standard hamburger. McDonald's is absolutely a rip off, but it's largely because they keep jacking up the prices, making tweaks to ingredient recipes to be more cost effective at the expense of quality, and removing low cost options.

https://www.snopes.com/fact-check/big-mac-since-1980/