In this tutorial, we'll go over the process of creating and styling contour lines in QGIS.
Here are a couple helpful recourses :
Download DEM Raster Files Directly from OpenTopography.org - https://youtu.be/iNsRYPHw69c
How to Add Additional Color Ramps in QGIS - https://youtu.be/WuEJGwFiBP8