According to Moz, Domain Authority is a score that ranges from 0 to 100 that predicts how well a website will rank on search engines. If you have a high Domain Authority, it means that your website has a good chance of getting good rankings if it gets listed in Search Engine Result Pages (SERPs). Page Authority, on the other hand, is a score measuring the relative "authority" of any given web page and is used as part of Google's page ranking algorithm.
Here are 10 Steps to increase Domain and Page Authority
Use link-building to increase your DA
Optimize your page titles and meta descriptions for search engines
Optimize your images for search results
Make sure your content is unique and relevant to your target audience
Update your site regularly, but make sure you don't overdo it!
Improve user experience with good design and straightforward navigation
Make sure you don't have broken links on your site (use the broken link checker tool)
Use social media for more inbound links to increase your DA and PA
Get links from other high-ranking sites(backlinko, neilpatel, search-engine-journal)
Try to do guest posts to improve your site's reputation and da pa score