That is the long answer. The short answer is how much do you have to spend?
Then we can pick out the best CPU/Motherboard/RAM combo that makes sense, or the full build if all you have is the GPU.
Ideally what you seek out is balance.
No point in putting a 1070Ti with a Core 2 Duo. It would work up to a point, but modern games that need something like a 1070Ti aren't likely to run well.
But you also don't need a 7950X to run a 1070Ti. When that GPU was launched CPUs like the 6th and 7th gen Intel were available, just before Ryzen 1st gen I think. So if you wanted to match conditions back then, something like an Intel i3-10100 or i3-12100 would be like having an i7 back then. Ryzen 2600 maybe.
But for the money right now that i3-12100 or a Ryzen 5500 would make the most sense in terms of budget.