I’m running OTRS 2.4.7 and I’m planning an upgrade. Do I need to upgrade throught 2.4.8, 2.4.9, etc. and all the way through every release, security or patch?
Read the doc.otrs.org Upgrading section.
You don't need to follow the path of all patches, but you need the minor releases.
2.4.x > 3.0.x > 3.1.x > 3.2.x > 3.3.x
I always use the latest available version (today is 3.0.22, 3.1.18, and so on)