Dual display like Asus-Project-Precog can convert current 13.5 inch into 27 inch laptop. without any major change.
I wouldn’t call this a 27 inch laptop. Two separate displays with a hard break between them. Is there the display square area? Yes. Can you watch a movie across both displays? Nope.
If there was going to be a second display, honestly an e-ink touch panel and/or Wacom compatible stylus receiver would unable most of the use cases people want without nearly the hit to battery life of two full color emissive displays.