Will This PC Be Bottlenecked at 1080p, or Should I Use 1440p?

The RX 9070 is arguably overkill for basic 1080p gaming, but that is not a problem. It gives you plenty of headroom for high settings and high refresh rates. You could simply play at 1080p with your desired settings and cap the frame rate if necessary. There is no requirement to switch to 1440p just because the graphics card is capable of it.

At 1080p, especially with competitive settings and very high refresh rates, the processor can become the limiting factor. Increasing the resolution puts more work on the GPU, so the GPU may reach full utilization before the CPU does. Your average FPS will normally be lower at 1440p, but that does not mean the system is performing badly—it simply changes which component is limiting performance. I’d also recommend 32GB of RAM for smoother gaming and better multitasking.

If you are targeting something like 500 FPS at low settings, a newer CPU platform could help more than changing the graphics card. For normal high-refresh-rate gaming, though, the 5800X3D is still a very capable processor. At refresh rates above roughly 240Hz, the practical benefit of chasing every additional frame is also fairly small.

Online bottleneck calculators are generally too simplistic to be useful. Your parts should work well together at both 1080p and 1440p. At 1080p, the CPU is more likely to limit extremely high frame rates, while at 1440p the GPU usually becomes the limiting component. The RX 9070 is powerful enough that 1440p would be a natural match, but you should still use 1080p if that is the resolution you prefer.