Answers
Short answer: the tiny text comes from one setting — Fit Sheet on One Page (or Fit to 1 page), which scales your entire sheet down until it fits, text and all. Turn scaling back off and let the sheet run onto more pages, or use a tool that re-lays-out at a readable size and paginates instead of shrinking. CrazySmartPDF does the latter.
The tiny-text problem is almost always a scaling setting:
100%. This undoes the shrink. Your sheet will now use as many pages as it needs.1 page, Height: Automatic (leave Height blank). That fits the width to the page but lets the height flow onto more pages — readable text, more pages.The honest catch: at 100% a wide sheet will now cut off columns instead (see convert Excel to PDF without cutting off columns). The two problems trade off against each other, and juggling them by hand on every file is the fiddly part.
It doesn’t scale the sheet to fit a page — it re-lays-out at a readable font and paginates:
Renders through your installed Excel on Windows (2016+); no Mac or purely-online path today (the web upload surface is a separate beta). One place text is deliberately trimmed: a very long single-cell value — a paragraph-length memo, say — is clamped to a few lines with an ellipsis (…) to protect the row height. It won’t reflow an essay inside one cell; it protects the layout of the rows around it.