Safari for iOS has kind of a "grace period" where the back gestures do work from the new tab. But I think this is more to aid the confusion for people who don't understand that a new tab has even been created.

If you switch tabs, or close the app, or do anything other than somewhat immediately go back, that back history is lost. And if you do use the shortcut to go back, the new tab is destroyed. There's no ability to open a bunch of tabs and then in each of them independently navigate back to the parent.