I think https://www.levels.fyi/ gives these classifications.

Here is Google's career ladder for software engineers: https://codingrelic.geekhold.com/2018/08/google-software-eng...

Your typical engineer with relevant education and 5 years of experience is probably about L4/5.

Even if he did get in, it seems unlikely that he'd be able progress beyond L5, after which leadership becomes more important.

I think the OP refers to Level 5 to Level 8 but I don't know what they mean either.