Game concept
Absolute Crown Authority
The game also links it as Absolute.
From the game's encyclopedia
Absolute Crown Authority is the highest level of Crown Authority. Vassals have a -30 Opinion penalty toward their Liege.
At this level — in addition to the effects of High and Limited Crown Authority — the ruler can pick a Designated Heir at a Prestige cost.
Furthermore, vassals cannot declare war even against foreign rulers.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Absolute Crown Authority is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Absolute Crown Authority is the highest level of Crown Authority." It is part of Crown Authority. The game also links it as Absolute. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.