How to use git to add the modification of each commit to the existing folder in a patch way, because the project is large, using clone or pull is very time-consuming and network dependent?

Thank you for your attention.

How to use git to add the modification of each commit to the existing folder
in a patch way, because the project is large, using clone or pull is very
time-consuming and network dependent?

Now,there is a linux kernel in my pc, and a branch of linux kernel in
github, I want to synchronize changes from remote repositories to my local
linux kernel.
And the local linux kernel is downloaded in zip format not in git mode. So,
Is there exists some method to do that.