Any study material on Classifications of SoC designs and corresponding costs?

I was working on an article about the increasing usage of Arm SoCs in the industry but I had a few observations that I wanted to understand better. I find it interesting to notice that there is such a huge variation behind the timelines, costs and team sizes among these numerous startups. While I understand that complexity of the use case will always be a big driver of costs I was wondering if there are some broad guidelines that dictate this. 

For example, what are the commonalities in SoCs that were developed in the $10-50M range vs those developed in the $50-100M range? Is it just the complexity that determines that, like AI processors and similar use cases needing more investment? Or the number of IC components being compressed together? If I want to think about this in terms of buckets then what would they be?

Thanks in advance for the help.