What is the best modern MMORPG engine?

Question

Game development

There is a plan for the development of a rather large and ambitious project, game mechanics, lore, etc. have been thought out and described.
In short, it's the closest thing to an open world MMORPG/Action format. Faced with the question - what kind of projects does it make sense to do at all?
If we want modern graphics (well, let's say not top, but at least at the level of Warhammer Vermintide on average), the presence of about a million players on the server and all sorts of sandbox game features (the same building, crafting, etc.)?

Answer 1

Now, relatively modern MMO RPGs are written in CryEngine (ArcheAge, Black Desert) - if it is a public engine, or on a private engine that will not be available to you either.
Bless, LOST ARK on Unreal Engine
New World is written on Amazon Lumberyard , it's supposed to be free. But obviously not very popular.

Answer 2

Well, maybe the platform on which the stalker is made is suitable