That's asking too much from a mere onneshot!! But here you go
https://www.mangago.zone/read-manga/my_father/ ( this one fullfill all your requirements)
https://www.mangago.zone/read-manga/a_pack_of_tissues/ ( all works of this artist are short and fking goated)
I kind of see it coming, but I had no business reading that first one on 1 am my goodness.....
Beyond my interpretation limits. But try these as well
https://www.mangago.zone/read-manga/time_letter/
https://www.mangago.zone/read-manga/49th_confession/
https://www.mangago.zone/read-manga/the_story_of_a_cat_that_has_lived_for_100_years/
its a manhwa BUT ITS SOO GOOD AND THE PLOT TWIST IS INSANE
a room without windows
please please please, I need a short manga (can be oneshot) that has a plot twist so fucking good it will make me edge
we have a film to shoot and I'm taking inspirations from your recos, please please please help a friend out