pdf-tools retina display for mac?

I'm using emacs-plus@27.2 on MacOS X 10.15. When I open pdf with pdf-tools, the image is not as clear as retina display should be. If I use emacs-mac then it is OK. But it should be the emacs-mac-port who fixes this.

I checked the doom code for pdf-tools. I found there is a section for retina display. I do not understand why this cannot work.

If I borrow the configuration from
https://github.com/seagle0128/.emacs.d/blob/master/lisp/init-reader.el
and add to `config.el`, then it works.

Maybe fix this?

**System Information**
https://pastebin.com/gM9zYdLY