This makes no sense to me!

I belive Video Games will always be developed for the most advanced hardware and than downported, therefore it's like:
PC > XBox Series X > PlayStation 5
3rd Party Games will be on consoles always be superior on the XBox Series X, which probably are around 90% of the available Video Games during a consoles lifetime
It’s the other way around, in 15 years of development I have never developed for the strongest hardware and then down ported it to match weaker hardware. This way creates way to many problems, imagine you are a Engine developer, you develop a engine that needs a minimum of 2.4 g/s of transfer speed from your storage medium (this is an example), how would you now bridge this deficit ? It is possible, but you would have to rewrite your entire engine around this problem. Which is why you look at each individual part of the platforms you release and then always take into consideration the weakest hardware.
Now the gpu is the easiest power deficit you can migrate, simply reducing the graphics fidelity will give the weaker hardware enough of a boost to bridge the difference in power (or resolution etc.).
The cpu on the other hand is more of a problem, where you really have to start putting effort into optimisation work, architectural difference is one problem but if there is also a significant power difference your problems really start to show (see ps3 and Xbox 360 for a similar problem).
Storage mediums are a huge problem and will be difficult to port for, if you require a certain amount of bandwidth. Imagine you really need the ps5 level ssd speeds and then you suddenly have to port your game to Xbox series X. This will create fundamental problems in streaming things into your game and the problem only increases when you take into consideration that on pcs most users still store their games on hdds. Now you have a real problem, for what kind of problems start to appear, watch the digital foundry video on playing star citizen with an Hdd. This game “only” requires a normal sata ssd to be played, imagine what would happen if your engine requires the ps5 ssd as a minimum, it would simply be unplayable.
These are examples why you always start with the weakest platform for each of the hardware components in mind and then start developing your game. That does not mean you cannot take advantage of the stronger hardware like Xbox Series X gpu or PlayStation 5 ssd, but you take the weaker hardware as the base for your development and then increase the fidelity and effects for the stronger hardware.
Multi platform games no doubt will look better on Xbox, but do not expect a huge difference in what can be done. Instead you will either see better graphics for example more foliage in an environment or better effects, more stable fps etc. See this generation for reference and remember this gen had a difference of ~40% while the next won’t even be 20%. So keep this in mind.
Cheers.