Question about the fans from a laptop?

Is it harmful if the fans of my gaming laptop run at max. Work when the CPU and GPU are not being used, or is it even good because it frees itself from the dust?

Rather bad. Because if he got rid of the dust, he would turn down after a short time. If necessary. Sits a layer of dust like a kind of membrane in front of radiator fins. This reduces the cooling capacity, since the fan can still turn.

The problem is, what does your gaming laptop do when the CPU and GPU are under load when it is already spinning? Heat protection with power reduction, of course. And you don't want that.

Is the laptop on a regular surface or, for example, your mattress because you watch Netflix in bed? So I wouldn't be surprised if the device turns up the fans despite little load. Mattresses store heat that the case emits downwards, which leads to heat build-up.

Thanks, but I related to it that I set it up manually.

Ok, I did misunderstand that. Thought it would turn to maximum by itself.
Then it is fine. With more drafts there's less chance that dust will permanently settle somewhere. And if the volume doesn't bother you, the only risk would be that the air bearing may eventually wear out faster and have to be replaced. But often not dramatically.