Tiered link building uses two levels of links to boost your website’s rankings....

https://www.bust-bookmark.win/tiered-link-building-organizes-your-backlinks-into-layers-to-boost-seo-more-1

Tiered link building uses two levels of links to boost your website’s rankings. Tier 1 links point directly to your site and should be high quality. Tier 2 links support those Tier 1 links, helping them rank better in search results