Comment by WorldMaker

Developers have tried to build metrics for "complexity" over the years. Cyclomatic Complexity is often pointed to as one of the more successfully deployed: https://en.wikipedia.org/wiki/Cyclomatic_complexity

As with any metric, it's something to take as useful "advice" and becomes a terrible burden if you are optimizing for/against it directly. (Such as if you are incentivized by a manager to play a game of hitting certain metric targets.)

It's also interesting to note that a complete and accurate complexity metric for software is likely impossible due to it being an extension/corollary of the Halting Problem.