>Not necessarily. Sony's early readers had automatic reflowing of text if you chose a larger font size. It worked really well for fiction or any other type of text without pictures/diagrams.
My first ereader was Sony's PRS-350. It had automatic reflowing, but it did a poor job on many PDF's. It did not take care of line breaks - so if I increased the font size, each line was 1.5 lines long (i.e. the original PDF's line would be 1.5 lines on the ereader - it would still respect the line break).
I haven't tried the conversions in recent versions of Calibre. I did try it for PDFs over 5 years ago, and the results were less than satisfactory. I pretty much decided not to use small ereaders for PDFs.
Not necessarily. Sony's early readers had automatic reflowing of text if you chose a larger font size. It worked really well for fiction or any other type of text without pictures/diagrams.
For modern e-readers, converters like the free Calibre software (https://calibre-ebook.com), will allow resizing & reflow of text in PDFs to a size more usable for any device.
>Sony used to make 9" readers ...
There are refurbished Sony PRS-900 units available (e.g. eBay) for around $50 and, unlike most e-readers, they have user-replaceable batteries.