kibana-123/src/ui/public/field_editor/field_editor.less

Kibana is an open source (Apache Licensed), browser based analytics and search dashboard for Elasticsearch. Kibana is a snap to setup and start using. Kibana strives to be easy to get started with, while also being flexible and powerful, just like Elastic

textarea.field-editor_script-input {
  height: 100px;
}