Can i use an extension wire/cord to charge my iphone?

So i just saw a comment saying that iphones should not be charge with their charger plugged in an extension cord/wire/outlet and should be on a direct source

So i have an outlet on my wall, then i plugged my extension wire/outlet and that extension was also has another extension wire/outlet so it can reached my bed. In the first extension, it consists of my 2 siblings charger and of course the extension to my bed. My charger was plugged to the 2nd extension, so it is just safe or would it bring damage to my phone not having base from the comments not charging to a direct source?