There are several varying ideas and functional adaptations in the area of control of iPad display.
In fact, some I've never tried with my iPad Mini1.1 (wi-fi) iOS9.3.4 because mine is used in the
association of a Mac and an iPhone. And some of these things are best done with better tools.
If full screen zoom isn't working the way you want on the iPad, here's a fix for the problem.
https://ipadacademy.com/presenting-with-the-ipad-problem-with-zoom-full-screen-c hanges-to-window/

We show you how to use Safari on the Apple iPad. Safari is the default web
browser on the Apple iPad. ... Double tap to zoom into a page;
knowyourmobile.com/apple/8474/how-use-safari-apple-ipad
Change screen resolution on your iPad ... But your iPad also comes in with an accessibility
feature that allows you to zoom in and zoom out from the image currently ...
ipodiphoneitunestutorials.com/iPadTutorials/change-screen-
Due to the changes during evolution and span of different iOS versions, these ideas also change
so what may work for iOS10. may not be what you wanted for an upgrade to iOS9.3. And later
hardware wouldn't know how the earlier iOS option worked; as that missed out on it entirely.
Several subtle and not so subtle ideas that may help your specific situation, that I've read about
but have not tried on iPad in iOS10.x. ~ Of those in search result some more likely appear here:
https://duckduckgo.com/?q=iPad+Safari+Zoom+Out&t=ffsb&ia=qa
While some newer ideas incorporated in later iOS version instructions may not retro to old
models, some do. The Apple iOS manual for iOS 11.4 updates older 11.3, free in iBooks.
..Sorry to not be of much help at nearly 2AM local..
Have been reading while writing; & not finding much.
