No it does not, at least not to the full engine and editor. Source access is separate and the price is unlisted, although rumours are that it's six figures:
Source is $40k up to 50 seats, and then it jumps to $100k. It's pretty obscene. The worst is that Unity will fight you if you say you need the source, like it's a crazy request.
Think how much are the salaries to fill 50 seats => $40k is a drop in the sea.
I can understand that this pricing model doesn't appeal to amateurs and micro teams working in their free time. I can also understand that Unity doesn't care about this [non] customer base.
https://store.unity.com/products/unity-pro