Doonald wrote:
I'm a bit lost on how to add a shortcut in the keyboard settings. I always add a shortcut to 'combine all windows into one' (or something similar in English). I use it a lot to clean the view. But I can not find it in Ventura. Hope someone can help me to give an instruction. thank you!
'combine all windows into one'...?
All windows would imply all applications, and this does not sound feasible.
If you are asking about a single application with multiple windows open—the exposé feature is an option(?)

ex TextEdit.app

4 finger swipe up is the Mission Control to see all open windows all open applications— but this is not "combine" as I understand it..(?)

ref:
See open windows and spaces in Mission Control on Mac - Apple Support