Elastic search "index-template" mapping definition (copy_to?)

I'm defining an index template for documents, which have unknown number of fields (the fields themselves are unknown as well).

I want to set mapping definition for the indexes, where I could perform (in the my site UI) a text search in the whole document (not case sensitive), a text search in each separate field (not case sensitive), and also sort by each field (there are all numbers or strings).

Is this the right way of doing that? by using dynamic_template and providing him:

[
    {
        "strings_as_keyword": {
            "match_mapping_type": "string",
            "mapping": {
                "type": "text",
                "fields": {
                    "keyword": {
                        "type": "keyword",
                        "ignore_above": 256
                    }
                }
            }
        }
    },
    {
        "numbers_as_double": {
            "match_mapping_type": "long",
            "mapping": {
                "type": "double"
            }
        }
    }
]

Should I maybe use copy_to for the full document search?

Tldr;

Yes, if you plan on heavily search through lots of fields you are better of aggregating all those fields in a single one.

Solution:

PUT 76433872
{
  "mappings": {
    "dynamic_templates": [
      {
        "strings_as_text": {
          "match_mapping_type": "string",
          "path_unmatch": "all_text",
          "mapping": {
            "type": "text",
            "copy_to": "all_text"
          }
        }
      }
    ]
  }
}