There are different packages for creating posters, including tikzposter, beamerposter, and sciposter which are intended specifically for the creation of conference posters.
This is a short guide to utilizing the beamerposter package for the creation of posters.
This is a short guide to the use of the a0poster package, and includes a template poster.
Overleaf provides the basic setup for creating a scientific poster using tikzposter and beamerposter.
GSU Library also has a guide called How to: Poster Presentations which provides further information on design.
