Personally from what I’ve seen in adequately-cooled Tiger Lake ultrabooks (which Framework appears to be), sustaining 15W puts the CPU Package temperature at 60-65C, while sustaining ~30W should be possible at 85-90C, a temp I consider to be safe to sustain for prolonged workloads.
@Kieran_Levin posted a screenshot of FurMark (a GPU-heavy load) running for 5 minutes on the 1165G7 and the temperatures looked remarkably low (28W@73C). So I’m curious about this discrepancy vs. the third-party reviews.
Intel has disabled the ability to undervolt 11th gen CPUs (at the hardware level, so no easy workarounds). That said, you should be able to use something like ThrottleStop (on Windows) to modify PL1 and PL2 values if you’re not happy with the values Framework chose. Also, since Framework claims the EC firmware is open-source, it theoretically should be possible to do this without any third-party programs.