What did he do to enable RGB?
For desktop icons you can just use CTRL+mouse scroll down to decrease icon size. Don't think text size will shrink. There should be other options in windows to increase decrease text size. Google.
There is an in Windows display settings called "scale and layout". Try that. But they are to scale up, I don't think there is an option for scaling down.
In AMD there is something called virtual resolution, there should be something similar in Nvidia too. You can use that to set your FHD display as 2k or even 4k. For 27", 2k would be fine.
In my 23" FHD display when I tried 2k/4k, texts are not as crisp as 1080p.