What is Off Page SEO?
It refers to work done after your site is complete. What left more? You need to build links with related websites. You have to write some posts on a reputable or good site as the guest blog. Also, mention your website name after the post. This will enhance your inbound links.
Moreover, You need to understand link building. When you write some good article then people love it and if any trusted website found that your content can give some value to their readers then they link to your site.