Tiered link building boosts your website’s authority by using multiple layers...

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

Tiered link building boosts your website’s authority by using multiple layers of backlinks. Tier 1 links point directly to your site, while Tier 2 links support those Tier 1 sources