It would depend on the triple-A title. For the time being, most GPUs still would not be possible to reach 200+ FPS if you're maxing settings at 1440p; even using a 3080. You might be able to in some titles if you reduce the graphics settings.
I'd recommend going with the one that fits your budget or what you can find available. If you're looking for 200+ FPS I'd go with the higher-end GPU.
I believe you'd be able to do so. Depending on your settings, EFT may have some difficulty.
Here's a video I've found with some comparisons using Ryzen processors with a 3080. I'd imagine the 3900XT would be a 1-3% increase performance from 3900. https://www.youtube.com/watch?v=tZFfaCoVKPs
Submit photos and a description of your PC to our build showcase
See other custom PC builds and get some ideas for what can be done
Services starting at $149.99