Tiered link building helps you build a strong backlink profile by layering...

https://seo.edu.rs/blog/how-do-i-build-tier-2-content-that-looks-natural-and-not-forced-11162

Tiered link building helps you build a strong backlink profile by layering links. Tier 1 are your main backlinks pointing directly to your site. Tier 2 links support Tier 1 by linking to those first-tier pages