Default Similarity Model for a Index

I am trying to figure out if I can configure the similarity model like BM25 as default for just a index in my Elastic installation.

I found that I can add a configuration setting for the whole Index in the YAML file like this, "index.similarity.default.type: BM25", but I want to configure it for a single Index. For example, I have 4 indexes currently,

  1. Customer1
  2. Customer2
  3. Customer3
  4. Customer4

All the above use the default similarity type. but for new Index "Customer5" I want to change the similarity to use "BM25". I know that I can set a custom one and give it for the fields that I want to use this similarity as mentioned in this document. But that is too cumbersome and with dynamic data it doesn't work well.

I am not sure how to satisfy my requirement b/c I couldn't find a document or discussion in the group. Please let me know if there is a way.