Most if not all WC wingers have some sort of transition.
Messi, CR, Neymar, Salah, Robben and Bale are examples of players who had obvious transformations. Most commonly the players become more central in different ways. Robben played mostly on the left before exploding as a pure RW.
Now we see Mbappe in that transitional period which for now looks like a mistake, but I'll give him a couple of months to adapt.
I think for most the change comes naturally (as opposed to Mbappe who's seemingly being shoehorned into #9). It's all about where the player is most efficient and for now Yamal is pretty efficient bar the goals. He's involved in chance creation and build up of the attack which I think is what suits him best. I'm not sure if he'd be better off at #10 for example, but it's not impossible he moves there later, otherwise a free role at RW suits him.