From the game's encyclopedia
Demand a Character's loyalty in the form of a Hook by using piety, guile, or intimidation.
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.
Demand Submission is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Demand a Character's loyalty in the form of a Hook by using piety, guile, or intimidation." It is part of Interaction. Patch 1.20.1.2, from game/common/game_concepts/03_fp3_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
for a guide, post or blog
Source: game/common/game_concepts/03_fp3_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.