Yeah they are.
It's more or less the Xbox One and Xbox One X but this time they're shipping both at around the same time.
So Xbox Series S will be the target and X will give you that extra oomph. However, game engines are also more tailored to this type of scaling nowadays.
In the end it'll probably look something like this at launch for most titles.
Xbox One: 30fps / 720p (dynamic)
Xbox One X: 30fps / 1080p (dynamic)
Xbox Series S: 60fps / 1080p - 30fps / 1080p + Ray Tracing
Xbox Series X: 120fps / 1080p - 60fps / 4k - 30fps / 4k + Ray Tracing
However, just like now most devs probably don't care if their games hit sub 30fps on Xbox One or sub 720p.
They probably are more tailored to this type of scaling, and I imagine that the hardware will be such that scaling is easier. Still though, I don't know... The one advantage a console has over a PC, for instance, is the ability to make a game specifically for one set of hardware specs. Which is why The Last of US part 2 looks so good for the relatively weak hardware it is running on. They are at a point now where they are able to squeeze every little bit of juice out of that hardware. Of course, yeah, there is the PS pro as well. However, the fact that the hardware was released years after means the circumstances are a bit different.
Maybe it doesn't matter. The fact that the two consoles will be tailored made, and I would assume, I hope even, the hardware will share similarities, that may mean scaling works pretty well between the two consoles. In PC gaming developers have to develop for a variety of different potential setups. However, I still feel a little uneasy about it. The base hardware will determine how big a jump graphically this gen will be across the board. Console gaming holds back the potential of PC gaming. And that only becomes more so further into the console cycle.