How to turn Block Extended layout in 4 Columns

Go to WordPress Dashboard >> Divi >> Theme Options >> Custom CSS >> add below code snippet.

@media screen and (min-width: 981px) {
.et_pb_post_extra.el_dbe_block_extended:not(.swiper-slide) {
    width: calc(24% - 6px) !important;
   margin: 6px!important;
  }
}

Output: