Implement different remote version of XMLConfigurationFactory, JsonConfigurationFactory and so on, to allow the possibility to download file configuration from remote URL o FILE.
In example you could use a file called log4j2.rjson and write on it where download the file:
content of log4j2.rjon is : http://127.0.0.1:8080/log
and get from that url a json configuration
In the same way you could use a log4j2.rxml to get the configuration in format XML:
content of log4j2.rxml is : file://path/to/file/xml
If this can be reasonable i can work on it