I don’t think you can skin ElvUi. I am not sure but I think you can make some pannels and put textures to it and that’s pretty much it. However, ElvUi allows a lot of customization of all possible panels so you can really adjust it how you see fit.
If you ask me, on original Ui I like those gryphons on action bar but 99,9999% of time I do not pay attention to it and you won’t pay much attention to ElvUis boxy style.
Here are few examples how people change their ElvUi.
https://media.wago.io/screenshots/SkqY9p1rX/5b624aa4414dc108ec5b36f3.png
https://media.wago.io/screenshots/rkzP24hK7/5baebd0f917bf57ec8fa91c2.jpg
You can change font styles on NPCS on Combat Texts, on quest logs, zones, everything. You can apply 3D profile to unit frames but if you have weak CPU it might have effect on performance. You can hide chat panels, toggle them and so on. You can see it on my ui.
This is how my Ui looks like:
> https://imgur.com/nJ2Q4h8