In Writer for iOS, you have different options to change the rendering of Preview: the fonts, layout or even background color.
You can choose between Web or PDF view.
You have more formatting options available for PDF via Settings → Templates.
In the Web view, you can invert the colors to mark the difference between the Editor and Preview. If the Editor is in light mode, Preview will appear in dark mode and vice versa.
You can modify the font and layout of the document in the Preview thanks to the Templates:
Preview determines what Export will look like. In the case of PDF, the currently selected typography in the Preview will be used.
Modify the Preview 
In Writer for Mac, you have different options to change the rendering of Preview: its size, fonts or even background color. Full-screen or Half-screen Preview can appear as half of the screen side-by-side with the Editor or in full screen. At full width, you can hide the Editor completely for an ideal reading environment, while
In Writer for iOS, you have different options to change the rendering of Preview: the fonts, layout or even background color. Web & PDF Modes You can choose between Web or PDF view. You have more formatting options available for PDF via Settings → Templates. In the Web view, you can invert the colors to
In Writer for iPadOS, you have different options to change the rendering of Preview: its size, the fonts, or even background color. Full-screen or Half-screen Preview can appear as half of the screen side by side with the Editor or in full screen. At full width, you can hide the Editor completely for an ideal
iA Writer for Android comes with a couple of in-app templates rendering in Preview. Preview determines what Export will look like. You can change the rendering of Preview by switching Templates. The ”template” button let you change the currently selected template. Thanks to those templates, you can modify the font and layout of the rendered
In Writer for Windows, you have different options to change the rendering of Preview: the fonts, the layout or even background color. Web & PDF Modes You can choose between Web mode (rendering HTML) or PDF mode: simply toggle ON and OFF the PDF mode on the top right of the Toolbar. You have more