How to compare branches in xcode

Yes you can compare file wise, just go to that specific file where you want to see modified changes by other branch.

Then you will see following bar in editor

on left side, select your own branch and on right side, select branch which has done modifications.

Then you can compare by commits, listed time wise just beside branch name.

In Xcode 12 you choose View->Show Code Review. You'll have two windows, one with the most current edits ("Local Revision") and the other lets you choose from various prior commits.