It requires a lot of work, and money to make your site a high authority

For me, improving your overall SEO efforts will help you improve your Domain Authority, also as well as your Page Authority. Just make sure to do proper optimization and follow SEO guidelines.

Domain authority depends on content quality and backlink quality and quantity. If you have good quality content then start building backlinks.

Domain authority will be built over time. You need to keep building backlinks to your website from high authority websites for several months and years.

Do properly on page and creating high quality backlinks.

Thanks For Your Information.