There are infinite combinations of CPU/GPU capable of running LLMs locally. What most people do is buy the system they can afford and roughly meets their goals and then ball-park VRAM usage by looking at the model size and quantization.

For more a detailed analysis, there are several online VRAM calculators. Here's one: https://smcleod.net/vram-estimator/

If you have a huggingface account, you can set your system configuration and then you get little icons next to each quant in the sidebar. (Green: will likely fit, Yellow: Tight fit, Red: will not fit)

Further, t/s depends greatly on a lot of different factors, the best you might get is a guess based on context size.

One thing about running local LLMs right now, is that there are tradeoffs literally everywhere and you have to choose what to optimize for down to the individual task.