develop and test your plugin for running on Java 11
Use or update to
https://github.com/jenkinsci/plugin-pom/blob/master/CHANGELOG.md#329 3.29 contains some updates to be able to build and run your plugins using Java 11.
Release a plugin specifically for Java 11
First, please avoid doing this.
If you really think you have a case where you need it, we encourage you to come over the Jenkins developers mailing list to expose your case and see if we can find another way.
If you really need it, TODO explain the way plugins can be limited to be visible only from instances running Java 11, etc.
run Jenkins using Java 11