It's not possible to zoom out in any way so that the document doesn't fill the whole screen. This is not a bug but a feature that is missing.
This is necessary for documents that are too big size wise.

I think the user has their reader set to automatically convert to "liquid mode" for documents.

I was about to request a zoom function but after seeing so many requests for "unzooming", zoom lock, etc. I tested this.

If the document is displayed using liquid mode, you can't zoom at all. You have to change your text size preferences which messes up the formatting.

When you're not using liquid mode, yes you can pinch/double tap to zoom, etc.

It honestly would be nice to be able to zoom in/zoom lock when using the liquid mode. Since the document is rendered to flow like a regular word/text document, it feels odd not being able to zoom in and out. Makes the user feel like the feature is missing.

Hope this helps to clarify.

oui s'il vous plait, créé un zoom arrière. Les PDF sont trop gros. L'application n'est pas utilisable pour des catalogue par exemple

Can change the size of the page more big and return it, but I can't make the page more small or I can't make it take the 70%. I want to do that because the letter are so big when I open the document and the pages take the size of the tablet.

Are you unable to pinch zoom or double tap to zoom in some PDF files? Could you please explain the issue being observed in detail so that we may understand the issue better?

Thanks,
Adobe Acrobat Team