As I understand it, a modern GPU is actually just a Turing-complete processor which happens to be heavily optimised for massively data-parallel workloads. (You can even buy "graphics cards" that don't generate any graphics!)
As I understand it, earlier graphics accelerators such as the legendary Voodoo 2 were fixed-function devices, hard-wired to do only 1 thing, but do it extremely fast. Back in those days, what features your games could have depended on your graphics card. If (for example) your graphics card doesn't have trilinear filtering, you can't have trilinear filtering! End of discussion. So (as I recall it) each new GPU would shout about all the fancy new features it has. [Today, of course, that's all a function of the software you're running, not the hardware that runs it. Oh, wait... hello RTX!]
What I'd like to know is, what did these fixed-function devices actually do? Which exact parts of the rendering pipeline are done by the GPU, and what still needs to be done by the CPU? I presume perspective projection and Z-buffering is done in hardware on the GPU. What else? When you turn around, who rotates the entire world mesh? The CPU or the GPU? Does the CPU say "render this polygon please" for each individual polygon? Or does it upload an entire mesh into the GPU's memory and say "render this mesh" each frame?