I don't want to convert newline code in GitHub Desktop for Windows

Yes, you can set core.autocrlf.

 git config --global core.autocrlf false

This setting can be true/input/false.

Note: Customizing 8.1 Git - Git Configuration (core.autocrlf is described below)

It depends on when the new line code changed.

If it changed when gitclone, you can change the settings, delete them all once, and do gitclone again.

If it changed at the time of commitment, it would be better to rewind the commit with git revert after changing the setting.