100c means you are either running at the most it can do, Orr more likely it’s thermal throttling to protect itself. Generally north of 85 is the concern area.

I would clean the fans and vents if you can, and make sure if there are vents on the bottom of the laptop that anything you put it on, be it a table or a fan, is solid. No soft surfaces.

I doubt you’ll do any actual damage to it, the inbuilt safety is pretty good these days, so it’s mostly just comfort and leaving performance on the table. If you can find the fan plates in a store to try them and see how much air they move, that would give you an idea as to which one is worth getting. You could also just point a pedastall fan at it, normally worth a couple degrees as long as it isn’t right against it trying to blow in an out vent.