The Kafka Integration Plugin, which moving forward is the source-of-truth for both the Kafka Input and Output plugins, has included Kafka client 2.4.x since v10.1.0.
The Integration Plugin runs on Logstash >= 6.5, and comes bundled with Logstash 7.5.
If you already have the integrated plugin installed, you can use the plugin manager to update to the latest version.
If your Logstash has the individual input and output plugins installed, you may first have to remove them before you can install the combined integration plugin.
This is a request to bump Kafka client to 2.4.0 (released in Dec 2019)