Doesn't that depend entirely on the specific RT solution? If they have, for example, twice as many "RT cores" as the equivalent Nvidia GPU , then the RT performance will be twice as great. Even if it's not quite as fast at rasterising.
If they're using AMD's patented RT solution, then you get a "RT core per TMU" of which there are 4 per compute unit. Turing, by comparison has only 1 RT core per SM (an SM and CU contain the same number of shaders, so I'll treat them as functionally equivalent).
So 56 compute units on the SX would have 224 RT cores. Which is 3 times as many as are on a Titan RTX. A 36 CU PS5 would have 144 RT cores, which is exactly twice as many as a Titan RTX.
If we're talking purely 4K gaming with traditional rasterisation....well the SX will be around a 2080, and the PS5 around a 2070(S). RT performance....we cannot be certain, cause we don't know what the hardware is capable of because AMD haven't detailed it yet.