The PS4 Pro is 4.2 Tflops but it's still Polaris/GCN2.0
The Xbox One X is 6.0 Tflops in Polaris/GCN2.0 too
The RX Vega 64 is 12.6 Tflops but it's GCN5.0
The RX 5700 XT is 9.75 Tflops with new Navi/RDNA.
we all know from the amd slides that RDNA is 1.25 times more efficient than GCN (Vega).
And Navi's 9.75 TF are 14% more efficient than Vega's 12.6 TF. This gives us a 145% higher performance Navi in terflops.
So it's simple if the PS5/Scarlett are 12 Tflops consoles it gives us approximately 2.4 times more power than the X.