Is decorators a thing?

I am running the latest version of OpenSearch and I am trying to find out if there is a feature that allows you to alter message fields during searchtime while preserving the unmodified message on disk. I have seen this before in Graylog (called Decorators), but I am not sure if OpenSearch has a similar feature that is called something else. Decorators

Any ideas? Thanks!

Maybe field masking? Field masking - OpenSearch documentation