1868, "sketch of the plot of a dramatic work," from Italian scenario, from Late Latin scenarius "of stage scenes," from Latin scena "scene" (see scene); earlier in nativized form scenary (1690s). The meaning "imagined situation" is recorded by 1960, in reference to hypothetical nuclear wars.
"decoration of a theater stage, disposition and succession of scenes in a play," 1770 (in a figurative sense), earlier scenary; see scene + -ery. Meaning "a landscape or view, general appearance of a place considered as a pictorial scene" is from 1777.
<a href="https://www.etymonline.com/word/scenary">Etymology of scenary by etymonline</a>
Harper, D. (n.d.). Etymology of scenary. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/scenary