elasticsearch/docs/reference/esql/functions/kibana/docs/reverse.md

REVERSE

Returns a new string representing the input string in reverse order.

ROW message = "Some Text" | EVAL message_reversed = REVERSE(message);

Note: If Elasticsearch is running with a JDK version less than 20 then this will not properly reverse Grapheme Clusters. Elastic Cloud the JDK bundled with Elasticsearch all use newer JDKs. But if you've explicitly shifted to an older jdk then you'll see things like "👍🏽😊" be reversed to "🏽👍😊" instead of the correct "😊👍🏽".