The “experimental webkit settings” page is perhaps poorly named - as this page includes advanced settings that influence many key configuration items.
Unless you know exactly what you are doing, or are a Developer, you might be well advised to leave these settings at default values. Many of these settings work with reverse logic - such that an associated setting when set to ON is actually disabled. Many of these settings only benefit from change in very specific environments.
Many of these settings will change with each release of iOS/iPadOS. Insofar as I am aware, there is not a definitive list of WebKit settings for iOS/iPadOS.
If you wish to learn more about these settings, you might be best advised to “Google” specific setting(s) in which you have an interest - being aware that, by their very nature, the explanation may be meaningless without expert knowledge of web development, networking and associated standards.