What the achievement asks
Renown 80 with all four covenants. Ten points, account-wide, both factions.
Eighty is the cap, so this is Kyrian, Necrolords, Night Fae and Venthyr all maxed. It sounds enormous and it is not, because none of the four starts from zero.
The catch-up does most of the work
Renown was built with a catch-up from the start: an item in Oribos grants a block of it outright, and the level that block brings you to rose repeatedly over the course of the expansion.
The practical effect is that joining a covenant now drops you a long way up the track rather than at the bottom, and the remainder comes from covenant callings and the campaign chapters you are doing anyway.
The achievement is flagged account-wide, and people confirmed it counting across characters. If you see a comment insisting it must all be done on one character, that is a guess rather than a report.
Do it alongside the campaigns
This is the same work as Dead Men Tell Some Tales seen from the other end. Campaign chapters unlock at Renown thresholds and reward Renown, so pushing one pushes the other.
Chains of Domination is the third in that group: its last chapter waits for Renown 58, which is on the way to 80 regardless.
Treat the three as a single job across four covenants and none of them costs anything extra.
Tracking it
The achievement's own criteria show which covenants are still outstanding. If the tracker is not showing them, this puts it on your screen.
/run AddTrackedAchievement(15646)