I don't know if this will help you visualize it or not, but here's a photo of someone using a TV as a monitor on a desk
https://i.imgur.com/mjcqjfZ.jpeg
I use my 4K TV as a monitor (though from ~8ft away) and for me Windows' scaling (found under Display in Control Panel) allow me to easily read text from so far away
Maybe it could help you
The benefit of a big TV should be that you can move it farther out than the 6" you mentioned (and that the person is roughly sitting at), increase text size, but need fewer neck movements to take it all in — provided you can focus at bigger distances.
You are essentially keeping the same angular size, and by moving an 85" TV to 19" from your eyes, you get text to be sized just like your 27" at 6" (3 x 27" = 81").
Won't help with your neck issues though, since you'll have exactly the same issues.
The issue with the "keyboard in front of huge monitor" type of arrangement for people who need to get their face really, really close to the monitor is they have to lean far in and hunch over the keyboard, putting their arms in an uncomfortable position. Speaking from my own experience, this causes RSI problems fairly quickly. And the keyboard can't be moved farther back to allow the person's arms to be in a more natural position because the base of the TV or monitor blocks the way.
A monitor arm of the right length and height lets you sit so that the monitor is close to your face, floating at or beyond the front edge of the table, and the keyboard is physically behind the monitor, letting your arms be in a more natural position for typing.