### Description

Dynamic mappings can greatly help the getting started experience but they currently don't apply to all types, one example is `dense_vector`.

It's been suggested to automatically map float arrays as dense vectors when there are more than 100 values, or a heuristic along these lines.
server/src/main/java/org/elasticsearch/index/mapper/DocumentParser.java
if (nested.isIncludeInParent() == false || parentDoc != rootDoc) {
                addFields(indexVersion, nestedDoc, rootDoc);
            }
        }
    }
    private static void addFields(IndexVersion indexCreatedVersion, LuceneDocument nestedDoc, LuceneDocument rootDoc) {
        String nestedPathFieldName = NestedPathFieldMapper.name(indexCreatedVersion);
        for (IndexableField field : nestedDoc.getFields()) {
            if (field.name().equals(nestedPathFieldName) == false && field.name().equals(IdFieldMapper.NAME) == false) {
                rootDoc.add(field);
            }
        }
    }
    static void parseObjectOrField(DocumentParserContext context, Mapper mapper) throws IOException {
        if (mapper instanceof ObjectMapper objectMapper) {
            context = context.createChildContext(objectMapper);
            parseObjectOrNested(context);
        } else if (mapper instanceof FieldMapper fieldMapper) {
            if (shouldFlattenObject(context, fieldMapper)) {
                
                String currentFieldName = fieldMapper.simpleName();
                context.path().remove();
                parseObjectOrNested(context.createFlattenContext(currentFieldName));
                context.path().add(currentFieldName);
            } else {
                fieldMapper.parse(context);
            }
            if (context.isWithinCopyTo() == false) {
                List<String> copyToFields = fieldMapper.copyTo().copyToFields();