IGP or dGPU?
I only have numbers for CPU and dGPU benchmarks (no IGP), but running Cinebench R23 single core for 20 minutes had the average Tctl/Tdie temperature at 80C on my FW16. R20 was the same at 80C @ 20m, and R24 was 81C (slightly higher ambient). I would assume that CB is a heavier pure CPU load than the game you were running.
However, if you are using the IGP for gaming, there is now much more heat being generated across the CPU die and the cooler is dealing with both CPU and IGP heat. It’s entirely possible, if not likely, that you might hit 100C under such scenarios.
I would run a pure CPU single core stress test and see what your temps are. I would also try raise the back of the laptop up a couple of inches to improve air flow. If you are still hitting 100C Tctl with no IGP load, it’s possible there is an issue with the cooler, cooler mount, or fans. There is also some variance between individual CPUs due to factors like the vcore needed to hit a given clock speed, but I doubt that variance to be more than a few degrees C.