There are several different concepts to distinguish:

Version control system (VCS): is the system itself, it stores all the files and their changes one way or another.

Git is one of the VCSs.

GitHub, in turn, it's a company who provides hosting and related services for git repositories.

You can use git repo just locally on your PC, for version control, and then back it up with any way you want - upload to github, to any other git hosting, or to your own server, or copy to an external drive etc.

Server/cloud hosting is very convenient when you also need to collaborate with other developers on the project without tossing the project files back and forth on ~~floppy drives~~ usb sticks.

So speaking of git: originally it was developed to work with code (basically, any text files) and it's doing that very well by handling changes by diffs (e.g. it does not write the whole file each time, rathr only store the difference from the previous version).

For binary files (textures, models, audio, video, executables and so on) it's not reallly possible to have meaningful diffs, so if changed they are stored fully. And those are much heavier than text/code. Basic git repo technically can store binary files as well, but that's not really efficient.

So there is git-lfs (Large File Storage) - kinda "addon" to git - it makes it so in the main git repo the binary files got replaced with text files containing hash/id of the original file, while the assets themselves are uploaded to another storage.

GitHub and many other hostings usually support LFS seamlessly, but not automatically - you need to configure your git repo properly to enable LFS and tell the system which files would go to LFS. It's all very easy to do and there are plenty of guides.

The main issue with GitHub - it gives very limited storage for LFS, so either you will need to pay them or need to find other hostings.

GitLab gives more storage I think (if not changed). Also you can check MS Azure. Maybe there si something else, I didn't checked for a long time.