To reduce the size of text (and images) in your web browser, press Ctrl and - together. (To make it bigger, press Ctrl and + together. To get back to the default size use Ctrl and 0)
To make a window take up less space on your screen (so that you can see the desktop as well) click the overlapping rectangles in the top right corner, then drag the edges of the window to obtain the required size.
Don't know whether you have this option but on my laptop at the bottom of screen are 4 icons. One is the tools option and shows a spanner. Clicking on this brings it up on the screen . Then I can do all kinds of things. Alter and adjust fonts, page size,delete history and numerous other things. All the things I can do in settings.