You'd be surprised by how much of a difference just cleaning the fans and applying new TIM will do. Preferably using a quality phase change TIM like those from Honeywell or Laird will work very well on devices like this.

I actually replaced the stock Liquid Metal on my ASUS Zephyrus with some Laird PCM and hot spot temps actually evened out towards the lower end and the low/high/average temps were the same after around a week or two of thermal cycling.