Hi
Omnisphere is not accessible in a traditional way, not even through controls view.
Aupresets you mentioned can be found online for free, but those are saved for very old version of omnisphere, 2.3 or something so those definitely won’t work on anything above version 2.5.
If you use komplete kontrol, you can purchase nks presets for omnisphere from freelance soundlabs for very low price, and that gives you even some control over the patches.
The only other way is natively, but only to audition and play presets as they are, there’s no control over them.
It’s simple, just use up and down arrow keys to move through presets. However, you should be aware that every time you load the omnisphere, there’s a splash screen showing versions for software, sound sources, and presets, plus available updates.
In order to use up and down arrow keys to go through presets, you should remove that splash screen. Use VOCR to OCR the screen, and going from above find a word Omnisphere and click on it with VO keys + shift + space and it will disappear. After that you can use up and down arrows.
Hope it helps.
Cheers