is it possible to filter results by similarity threshold?

Question

i used in mappings file a dense_vector for knn

   "esvector": {
        "type": "dense_vector",
        "dims": 768,
        "index": true,
        "similarity": "cosine"
      },

I want to use a similarity threshold , but it does'nt work for me , i dont find the way of using this threshold

payload['query'] =my_complex_queries
        payload['knn'] ={
                    "field": "esvector",
                    "query_vector": vector_field,
                    "candidates":100,
                    "k":5,
                    "similarity":0.5
                  }