CPUs are designed to fluctuate constantly and do so all the time under normal workloads. They're solid-state devices, not mechanical, so it doesn't negatively affect them, and the fluctuations won't harm them at all. Overheating will harm them, but modern CPUs are designed to throttle to prevent that, and will even shut down if they're not able to keep the temperature below the point where damage will occur. Running them at very high temps for a long time will probably reduce their lifespan, but not in any practical way, e.g. you could probably run it at 90C 24/7 for years, and running it hot on a regular basis might make it last 10 years instead of 15, at which point it would be long obsolete anyways.

The purpose of the CPU behaving this way is to try and quickly get a task done so a) user wait time is reduced and b) the CPU can return back to a lower-power state sooner, theoretically using less power overall. It's meant for very brief tasks, like opening a program. These tests can be misleading because they make it seem like the CPU isn't performing properly, but the boost isn't meant to last. It just lasts an even shorter time in notebooks, especially very small ones, because they don't have the same cooling capacity as a desktop. But ultimately, they're performing as intended.

The bottom line here is that you don't need to worry about it or use any special programs, just trust the CPU to do what it's designed to do, including protecting itself.

Would the CPU fluctuations seen in the looped Cinebench R15 test be of concern for damaging the CPU?

If the laptop can't cool the chip properly, could using the laptop for extended hours (e.g. like docked, being used as a desktop replacement) cause damage to the CPU due to the constant boosting then overheating and throttling? Maybe some sort of power limit or ThrottleStop program may help with this?