Well normally referring to the beauty in an anime opening, people generally consider elements like the song or the visuals
However, there's something I like in them other than the elements I mentioned above that being how they represent/connect to their respective stories
Well what I'm going to say below might (well 90%...) be stupid, bizarre and make no sense whatsoever but bear with it for a while
So one of the animes almost everyone has watched is Spy X Family so here's how the second opening of it links to the story from my point of view
So as you can see in these two scenes, Yor and Anya are represented with a pale-ish and dark background which could probably point to the loneliness in their initial lives
In this scene Loid has the same kind of background but a bit more vibrant
Also note he's in a train which is moving which could probably refer to the life of the Forger family after he came into the lives of Anya and Yor
Well there are a lot more of these throughout the opening and even the lyrics of the song but this small example should be enough ig
Here's another example from the 6th opening of Bleach
As you can see throughout the most of the opening, it's all black and white and if you remember it is around the time of the Arrancar arc when Ichigo and the others were in a dire situation outmatched
To me this theme represents the vibe of the part of the story really well
Well that's it for my part ig
You can criticize it if you think it is stupid and stuff
And in case you somehow find it interesting, try finding this factor in any other anime opening you've watched