This snippet will support auto advancing pages in multi-page form for radio button and drop down field types. Full tutorial here: https://gravityranger.com/how-to-build-a-conversational-form-in-gravity-forms

auto-advance-radio-select-fields.js

<script>
 jQuery(document).ready(function($) {
 $('input[type=radio], select').on('change', function() {
 $(this).closest("form").submit();
     });
   });
</script>