I changed the elasticsearch.yml file, and added index.similairty.default.type: BM25, and rerun the elasticsearch executable file. Is it the right way to change similarity measure? My data are very big, I don't want to re index the data

I changed the elasticsearch.yml file, and added index.similairty.default.type: BM25, and rerun the elasticsearch executable file. Is it the right way to change similarity measure?
My data are very big, I don't want to re index the data.