is there a way to control fan speed of a whatsminer ?
Using the stock firmware, no.
however, there is really no reason to adjust the fan, after playing with hundreds of Whatsminers I released that the fan speed is handled perfectly unlike many Antminers ( the stock firmware to be exact). if the fans are running slow and you think the miner is getting hot, you are wrong, the miner is at the temps it wants to be at, and the same thing goes for the opposite side of the story, if the fans are running too fast, they are keeping the miner at the temps where they think it's safe.
I understand you might want to adjust that on Anminter since based on my own experience all those s9s, T17 and S17 had some weird fan/temp ratio, but this isn't the case with Whatminers, in fact, I think even the custom firmware I mentioned above don't allow that, the fans can be unplugged and you tell the miner that it's going to dive into a tank for immersion cooling (it will stop checking for fans), or you let the miner control them.