using same git crypt key in multiple repo

Question

I had key for Repo:1

I had created another repository and create hello world project and push the changes.

Steps : here

1. Copy the key and added to the root project.
2. Add .gitattributes file with [file pattern] attr1=value1 attr2=value2
3. git-crypt status -> log does shows that it does encrypt the file.
4. Push the code to github. but file is not encrypted on github

do i need to do any settings on github externally?