If you create a blog on a high-ranking site with a domain authority of 77 and use it to link back to your site, it could potentially help improve your SEO. However, the impact depends on several factors:

Relevance and Quality: The blog content should be relevant to your niche and provide genuine value. A natural, contextual link to your site is more effective than forced placement.
Avoid Spammy Domains: Ensure the site where you’re creating the blog isn’t flagged for spam or involved in questionable practices, as this could harm your site's reputation instead of helping it.
Anchor Text Strategy: Use varied and natural anchor texts for your backlinks to avoid over-optimization.

For example, if you’re working on a site like Fix My Speaker that focuses on improving phone speaker performance, your blog could discuss mobile maintenance tips and link back naturally to a relevant page on your site as a recommended resource.

Always prioritize quality and authenticity over quantity to build a sustainable backlink profile