If you want even more immersion, consider adjusting your traffic density settings in the game's config.cfg file to see more of these beautiful models at once.
Installing the pack is straightforward for any ETS2 veteran: TRUCK TRAFFIC PACK BY JAZZYCAT V8.3 1.46
You don't need to overwrite any original game files; these trucks are added alongside the default ones. If you want even more immersion, consider adjusting
Move the files into your Documents/Euro Truck Simulator 2/mod folder. Activate the mod in the within the game. If you want even more immersion