Code Review process in tfvc 2012 or tfvc 2017?

Is there any option for code review and auto merge code after code review completes in tfvc 2012 or tfvc 2017? Is there any option of pull request in on primise TFS 2012/2017?

Yes for code review ,auto code option was not available in TFS2012,for TFS 2017 The Auto-complete option is available in VSTS and TFS 2017 and higher, and is only present when you have branch policies as defined while creating a project.
Yes pull request you can use in git/tfs in on promise with option of get latest/get specific in tfs,pull as per the git commands.