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

https://reidsinterestingthoughts.timeforchangecounselling.com/what-anchor-text-should-i-use-for-tier-2-links-pointing-to-tier-1

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