To change the size of the images (and therefore the height of the slider) you have to edit some code in functions.php you have to change the image sizes in these lines. To be precise, we recommend you to override the code using the child theme:
add_image_size( 'jumbotron-slider-l', 1920, 580, true ); add_image_size( 'jumbotron-slider-m', 960, 290, true ); add_image_size( 'jumbotron-slider-s', 480, 145, true );
Then you have to regenerate the images with this plugin: https://wordpress.org/plugins/regenerate-thumbnails/
That will change the slider height.