The page dimensions in a L a T e X document are highly configurable and the geometry package offers a simple way to change the length and layout of different elements such as the paper size, margins, footnote, header, orientation, etc. Suppose you have to create a document in a4paper and the text shouldn't exceed 6 in width and 8 in height. To create it with geometry is easy, include this one line in the preamble:. The parameters passed to the command determine the layout. In this case a4paper establishes the paper size and the total parameter determines the size of the text area. Open an example of the geometry package in Overleaf.
LaTeX and the document class will normally take care of page layout issues for you. For submission to an academic publication, this entire topic will be out of your hands, as the publishers want to control the presentation. However, for your own documents, there are some obvious settings that you may wish to change: margins, page orientation and columns, to name but three.