I've posted performance stats from my Razer Core X Chroma + RX 5500 XT with both 2019 16" i9 2.4GHz 5300m and 2019 15" i9 2.3GHz 560x setups. But here are some more stats and commentary.
The first three images show CPU utilisation, frequency, and left side fan speed under real-world everyday usage.
First (on the left) is me compiling 24 builds of a game (4 variations, 6 platforms) in Unity. This does not hit all CPU cores, but it does sustain close to 4GHz with minimal fan noise (momentary peaks at or just under 3000 rpm).
Then there's a period where the system was idle (I went away and came back) before (on the right) you can see me compiling 4 builds in Xcode. This DOES hit all CPU cores, with a pause in between each build step. This still sustains an amazing level of CPU performance at around 3.75GHz, with very high fan speed (but not pegged at max).
The next three images show performance under sustained synthetic heavy load (Cinebench R20 on loop). In this extreme test, the CPU can sustain 3.3GHz indefinitely with the fans pegged at max. It's also important to note that I can concurrently run the Luxmark GPU stress test on loop at this point with absolutely ZERO impact to CPU performance.
That's a key benefit of an eGPU over dGPU (even the 5600m). GPU heat and power consumption are OUTSIDE the machine's thermal envelope.
So in summary, IF you can live with having to click a "disconnect" before unplugging and having a few apps quit (only the apps that are using eGPU), an eGPU is an EXCELLENT way to workaround any heat/noise issues AND get the absolute best CPU performance possible from the machine.
It's cheaper than a 5600m upgrade (but still expensive), and can be added on after the fact, and upgraded separately.
The Razer Core X Chroma also gives you a "one cable" docking solution. I've heard reports that the ethernet is flaky, but I don't use that and I haven't had any issues connecting SSDs to the eGPU's USB ports for backups.
It also provides a full 100W of power to the machine which is important to prevent battery drain/degradation. Most monitors and TB3 docks only provide 87W or even 60W. The 16" MBP comes with a 94W power supply, but the next image shows the total system can use >=110W in bursts.
I don't buy into the argument that disabling turbo boost or setting a low total power limit with Volta and Voltage Shift has little or no impact on performance.
Obviously you won't notice it in all but the most extreme cases of slowdown, because you're too busy actually working. It's generally hard to notice the absence of something, anyway.
But from my own personal experience, I often DO notice that the performance IS available and is being used. I am frequently impressed that things just happen quickly, all the time. Not only massive compile jobs. Everything. Even everyday single core medium load tasks are happening at close to 4GHz. That's a 66% increase over the base frequency.