Does change in similarity class needs reindexing

[YOGENDRA SONI]

Hi all,
I am experimenting with different parameters of BM25 and Sweetspot
similarity.
I changed solr field type definition  like given below.
I need clarification that changing similarity in field type need reidexing
or not.
{"replace-field-type":{
"name":"content_text",
"class":"solr.TextField",
"positionIncrementGap":"100",
"similarity":{"class":"solr.SweetSpotSimilarityFactory",
"min":3000,
"max":4000,
"steepness":0.5},
..
..
..