Is there any other champions that changes their appearance from items/etc? Considering that such don't have/wear skins.
E.g Cho'g and Zac's size depends on their HP, that they grow large enough if they reach like 3k+ HP or something.
Another is Rengar who changes his appereance from gaining stacks on his Necklace (I don't know if this is true but I'm around 80% sure that he gains something new on his apperance from stacks).
Best Answer
Currently there are no champions that change their physical appearance depending on the Item they buy.
However there are some cases in which special audio or visual effects are triggered:
Primetime Draven
If you buy Different Items on Draven he will often use a quote:
Shopkeepers on Howling Abyss
Sometimes buying an Item triggers a special Quote
Items that have Visual effects
Now this is the same for all champions. As far as I know there are no Individual exceptions.
Champions that passively change their appearance
These Champions change their appearance passively according to Situation.
Now these may not be all the Items/Champions/Actions that there are in the game but if you take a look at the wiki, you will usually find some additional information to it. Also I'm pretty sure that Rengar doesn't change his appearance based on how many stacks he has (Can't find a reference and also from Personal experience).