How can I change a document size in Google Drive on iPad?

When I open docs in Google Drive they are one unchangeable size. If I pinch them, they will shrink, then immediately return to the size they were when I remove my fingers. Discussions recommend I tap the 'more' menu via the three dots then tap on zoom. I have. There is no Zooom option.

[Re-Titled by Moderator]

Original Title: how do i change view size of document on google drive