Event / hook where I can check for log event size before it gets logged

I am using serilog, and facing issue with ElasticsearchSink when a batch exceeds 10MB payload, I am on AWS ES service which restricts more than 10MB log. Is there any hook where I can check if a particular log entry is more than x bytes? I would like to skip such log events and replace it with a smaller log entry to say too big log message was generated and truncated. 
