A supposed listing for an Apple M1 successor has surfaced on a benchmark site, though it's likely that the chip's specifications are a prediction rather than the results of a test.
The "M1X" chip is said to be a 12-core Apple Silicon CPU. As an iteration on the M1, the chip features 12 cores instead of its predecessor's eight. Its internal GPU features 16 cores, instead of the 8-core GPU in the M1.
This is according to an alleged benchmark of a "pre-sample" of the "M1X" that appeared on CPU Monkey. It's impossible to independently verify whether the specifications are accurate, so it's likely wiser to take them as a forecast rather than a true leak of the next-generation Mac chipset.
The specifications do appear in-line with what Apple could release this year. The "M1X," according to the listing, is still a 3.2GHz chip based on a 5-nanometer production process.
If the prediction turns out to be accurate, it looks like the upgrade would be focused on graphics. The listing suggests that "M1X" could have a 16-core GPU with 16GB of maximum memory. It could feature 256 execution units, rather than the M1's 128, and may be able to drive three displays instead of two.
That makes sense because of the first devices that the "M1X" is supposed to appear in. According to CPU-Monkey, the "M1X" will debut in the second quarter of 2021 in a 14-inch MacBook Pro, 16-inch MacBook Pro, and 27-inch iMac refresh. Compared to the previous chip, the "M1X" is also rumored to have a higher power draw with a TDP of 35W instead of the 15W M1.
Again, these specifications are impossible to verify as authentic at this point. And CPU Monkey doesn't appear to have much credibility among benchmarking sites. But, at the very least, the supposed updates seem realistic.