does iphone 8 fit iphone 8 plus case

If you are asking can it fit properly, then the answer is no. The iPhone 8 Plus case will be too large.

here they are side by side https://s.yimg.com/uu/api/res/1.2/omqs8g10ylS5wloXPA3r.Q--~B/Zmk9ZmlsbDtoPTU1ODt3PTg3NTthcHBpZD15dGFjaHlvbg--/https://o.aolcdn.com/hss/storage/midas/c61d0186d816be35eb14cec14b881e41/205681454/_MG_2934.jpg.cf.jpg

so it would fit inside the 8 plus case but you would have to use duct tape to keep it from falling out