I need help for the clean up of my Zephyrus Gx701 Laptop

I would not consider the GX701 a new DIYer friendly laptop in terms of the thermal paste - you have to take apart quite a bit of the laptop in order to change it. If you want to see how to do it, refer to this video and see if you’re comfortable doing so, or you want someone with more experience to do the thermal paste. There are no guides here so this is about as good as it gets - I’m not surprised since these are so expensive. It’s one of those where I could do it, but I’ve also done laptops which require motherboard removal or major disassembly so I have a few “major disassembly required” ones under my belt - it’s nothing to me; just another machine I need to do major work on to change paste.

However, the fans are pretty easy to clean - remove the bottom cover which reveals access, blow canned air in the cooling system and then that will remove most of the dust from the fan and heatsink. Generally speaking cleaning is fine if it’s less then 3-4 years old, although the paste often degraded enough after 2 years you might as well get it over with on the easy ones with a major service.