to getting high Domain authority you need Quality backlinks and traffic,
so without backlinks, it's not possible to get high ranking. otherwise, using Blackhat techniques for getting high domain authority. but it's not a safe way. any time you might be banned by the search engine.
other ways which are increasing domain authority that, use high ranking keywords. and properly On-page SEO techniques. it can help for traffic.
Content also useful to getting traffic on your site.