I remember using Tasword Two for the ZX Spectrum. Even with a 3x7 font (4x8 grid) it only achieves 64 characters per line. Apparently in Tasword III the authors implemented 128 characters per line - by scrolling.

Competitors could apparently show 80 characters per line, but only by switching to a horribly unreadable 2x7 font. "I found the tiny 80 column characters tiring to read but the mode is useful if you want to see what the finished output will be like." - https://www.crashonline.org.uk/31/words.htm . I can't find a screenshot.