Elasticsearch allows you to configure a scoring algorithm or similarity per
similarity setting provides a simple way of choosing a similarity
algorithm other than the default TF/IDF, such as
Similarities are mostly useful for
text fields, but can also apply
to other field types.
Custom similarities can be configured by tuning the parameters of the built-in similarities. For more details about this expert options, see the similarity module.
The only similarities which can be used out of the box, without any further configuration are:
similarity can be set on the field level when a field is first created,