[dfawcus]

It does, if you interact at the CLI, where a "PR" concept does not exist.

   git diff ^initial-commit~1 final-commit

However for that to be available after a contribution has been included in the master branch, one has to use merge commits.

Otherwise there are no inherent markers as the graph has been flattened in to a linear sequence. One then has to make use of external tools, or commit comment conventions to recreate what was actually done or intended.