Just try to apply flex none to the div to keep their size and a specify media query where you want desktop to start.

.images {
    display: flex;
    align-items:center;
    background-color: #eee;
    padding: 1rem;
    overflow-x: scroll;
}

.images > div {
    flex: none;
    max-width: 100%;
    padding-left: 15px;
    padding-right: 15px;
}

.images img {
    max-width:100%;
    width: 100%;
}

@media (min-width: 960px) {

  .images {
     overflow-x: visible;
  }

  .images > div {
    flex-basis: 0;
    flex-grow: 1;
   }
}