does this work?
.lay-carousel{ height: 300px!important; }Enter this css in "lay options" -> "custom css & html" -> "custom css for mobile"
or
how about for the mobile version you create a custom phone layout?
https://laytheme.com/documentation/custom-phone-layouts.html
and have carousels with a different sizing in there
or you could always use a portrait aspect ratio photo as the first in your carousel.