How to adjust the font size of e-books?

On Android devices, you can select [Adjust Font Size] from the three dots in the upper right corner. This function is not supported on iPhones. Adjusting the font size in this way only works for e-books in EPUB format and is not supported for PDF format. For PDF e-books, you can use two-finger gestures to zoom in and out. Additionally, you cannot turn the pages when the e-book is not in the normal proportion. The normal left-right page-turning function will be restored after you return to the original proportion.