Tiered link building uses two levels of backlinks to boost your site's...

https://lilysbestblog.theburnward.com/how-do-i-build-tier-1-links-if-no-one-accepts-guest-posts-in-my-niche

Tiered link building uses two levels of backlinks to boost your site's authority. Tier 1 links point directly to your site and carry the most value. Tier 2 links support those Tier 1 pages, helping increase their strength and improve your rankings