While most LaTeX distributions are not well-suited to making posters right out of the box, there are many LaTeX packages designed to add that functionality. The two most popular seem to be beamerposter, which is a modification of widely-used slide deck package beamer, and tikzposter, which is based on the powerful tikz package for creating graphics in LaTeX.

For more information on packages and how to install them, the WSU Library's guide on LaTeX includes some basics: 

beamerposter

The package beamer is one of the most popular options for creating presentation slide decks in LaTeX. beamerposter is a modification of that package that takes each slide and turns it into a content box on a poster layout.

The paper "Writing posters with beamerposter package in LaTeX" from The PracTeX Journal, linked below, gives a detailed description of how to create a scientific poster using beamerposter, and Overleaf (a cloud-based LaTeX editor) contains a number of poster templates built using beamerposter.

The following code snippet can be added before the poster's title to change the color scheme:

\definecolor{WSUgreen}{RGB}{0,89,79}
\usecolortheme[named=WSUgreen]{structure}

tikzposter

The package tikzposter is based on TikZ, a package which allows for the creation of coordinate-based diagrams or graphs. Though TikZ can be moderately difficult to work with, tikzposter is much simpler and does not require the user to be familiar with TikZ.

The documentation for tikzposter provides detailed instructions for setting up a poster and Overleaf, mentioned above, also contains multiple poster templates built using tikzposter.

LaTeX (pronounced LAY-tech) is a document markup language which was developed to make it easier for scholars to create and format their own books and articles, and has traditionally been focused on mathematics and the physical sciences. Researchers and graduate students in those disciplines may already be familiar with LaTeX, and its broad use makes it a good option for creating posters.

If you're new to LaTeX, have a look at the WSU Library's guide, which should take you through the process of getting it up and running and provides links out to a wealth of resources:

After Mike Morrison introduced his conceptualization of a "better" research poster in early 2019, a LaTeX documentclass was developed by Rafael Bailo, a postgraduate researcher at Imperial College London. The source code and accompanying documentation are available on GitHub, and a template for this implementation of the betterposter concept is also available on Overleaf.