Update non dynamic settings

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
Elasticsearch 6.8, 6.3

Describe the issue:
I want to add 1 more analyzer into the setting. But the OpenSearch returns

[401] {"Message":"Your request: '/my_index/_close' is not allowed by Amazon Elasticsearch Service.

I’m using ruby on rails.

My script is below

Email.__elasticsearch__.client.indices.close(
        index: Email.index_name,
        type: Email.document_type
      )

      Email.__elasticsearch__.client.indices.put_settings(
        index: Email.index_name,
        type: Email.document_type,
        body: {
          settings: {
            analysis: {
              analyzer: {
                email_tags_analyzer: {
                  type: 'custom',
                  tokenizer: "email_tags_tokenizer",
                  filter: ['lowercase']
                }
              },
              tokenizer: {
                email_tags_tokenizer: {
                  type: "ngram",
                  min_gram: 3,
                  max_gram: 10,
                  token_chars: ["letter", "digit", "punctuation", "symbol"]
                }
              }
            }
          }
        }
      )

      Email.__elasticsearch__.client.indices.open(
        index: Email.index_name,
        type: Email.document_type
      )

      Email.__elasticsearch__.client.indices.put_mapping(
        index: Email.index_name,
        type: Email.document_type,
        body: {
          properties: {
            email_tags: {
              type: 'text',
              analyzer: "email_tags_analyzer",
              fielddata: true
            }
          }
        }
      )

Configuration:

Relevant Logs or Screenshots:

It seems that close api is forbidden in AOS: Supported operations in Amazon OpenSearch Service - Amazon OpenSearch Service

I have researched a lot and got the same result. Seem like I don’t have any choice.