There are a lot of factors you need to consider to achieve high PA and DA, most especially on improving your sites onpage optimization first.
First things first, make sure you have correctly linked your site pages internally.
Second would be your site URL structure, its navigation, categories and subcategories.
It will not be just easier for search engines to crawl/index but also and most especially for your audience.
Having a great content too can play an important role, most especially if it is linkable/shareable, it's an advantage (so you know what to do).
Link building alone, on the other hand is not anymore effective especially if you do it just for the sake of having a backlink to your site.
Link building, engagement and establishing reputation, all works together effectively.