This article breaks down how tiered link building works by using Tier 1 links...

https://www.nav-bookmarks.win/tiered-link-building-scales-seo-safely-by-pointing-quality-tier-1-links-to

This article breaks down how tiered link building works by using Tier 1 links to boost your main site’s authority and Tier 2 links to support those Tier 1 pages