I know your message is from August, but just in case here is my 2 cents.
I own the "Red Devil" Vega 64 version of this card. It's 2.7 slots card, that won't fit in most of the eGPU enclosure except Razer Core X which is 3 slots.
Even in my ATX case the card sort of lean on the right due to its own weight!
The card pulls 230W at full load with standard non OC bios, measured from GPU-Z, so again there should be no problem with the Razer Core X with its 650W PSU.
If you don't mind the noise, it's possible to get 15% more performance with OC, fans 2500rpm, a slight undervolt and a higher power limit (in Wattman).
I suppose Vega 56 should be even easier as its power consumption is lower than 64.
Thanks for the information.
I will look at the Razer Core X box.
RE: Even in my ATX case the card sort of lean on the right due to its own weight! - yes not surprised.
You should probably get a support bracket for it.