### 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
) throws IOException {
            super(
                mappingLookup,
                mappingParserContext,
                source,
                mappingLookup.getMapping().getRoot(),
                ObjectMapper.Dynamic.getRootDynamic(mappingLookup)
            );
            if (mappingLookup.getMapping().getRoot().subobjects()) {
                this.parser = DotExpandingXContentParser.expandDots(parser, this.path);
            } else {
                this.parser = parser;
            }
            this.document = new LuceneDocument();
            this.documents.add(document);
            this.maxAllowedNumNestedDocs = indexSettings().getMappingNestedDocsLimit();
            this.numNestedDocs = 0L;
        }
        @Override
        public Mapper getMapper(String name) {
            Mapper mapper = getMetadataMapper(name);
            if (mapper != null) {
                return mapper;
            }
            return super.getMapper(name);
        }
        @Override
        public ContentPath path() {
            return this.path;
        }