example

PUT _component_template/base
{
  "template": {
    "settings": {
      "index": {
        "number_of_shards": 1,
        "number_of_replicas": 3
      }
    }
  }
}
 
PUT _component_template/with_time
{
   "template":{
      "settings":{
         "index":{
            "sort.field":"date",
            "sort.order":"desc"
         }
      },
      "mappings":{
         "properties":{
            "date":{
               "type":"date",
               "format":"yyyy-MM-dd"
            }
         }
      }
   }
}

PUT _index_template/myindex
{
  "index_patterns": [
    "myindex*"
  ],
  "composed_of": [
    "base",
    "with_time"
  ]
}

PUT myindex
GET myindex

results

# PUT _component_template/base
{
  "acknowledged" : true
}

# PUT _component_template/with_time
{
  "acknowledged" : true
}

# PUT _index_template/myindex
{
  "acknowledged" : true
}

# PUT myindex
{
  "acknowledged" : true,
  "shards_acknowledged" : true,
  "index" : "myindex"
}

# GET myindex
{
  "myindex" : {
    "aliases" : { },
    "mappings" : {
      "properties" : {
        "date" : {
          "type" : "date",
          "format" : "yyyy-MM-dd"
        }
      }
    },
    "settings" : {
      "index" : {
        "number_of_shards" : "1",
        "provided_name" : "myindex",
        "creation_date" : "1586481768318",
        "sort" : {
          "field" : "date",
          "order" : "desc"
        },
        "number_of_replicas" : "3",
        "uuid" : "lvRDQ9y5Th-0zCH6yjEMZg",
        "version" : {
          "created" : "7080099"
        }
      }
    }
  }
}