Tiered link building boosts your site’s authority by using two levels of links....

https://sierra-wiki.win/index.php/How_Do_I_Keep_Tiered_Link_Building_from_Turning_into_a_Link_Pyramid_Scheme%3F

Tiered link building boosts your site’s authority by using two levels of links. Tier 1 links point directly to your site and should be high quality. Tier 2 links support those Tier 1 pages, making them stronger in search rankings